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* thp: split_huge_page_mm/vmaAndrea Arcangeli2011-01-135-0/+5
| | | | | | | | | | | | | split_huge_page_pmd compat code. Each one of those would need to be expanded to hundred of lines of complex code without a fully reliable split_huge_page_pmd design. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: pte alloc trans splittingAndrea Arcangeli2011-01-132-9/+18
| | | | | | | | | | | | | | | pte alloc routines must wait for split_huge_page if the pmd is not present and not null (i.e. pmd_trans_splitting). The additional branches are optimized away at compile time by pmd_trans_splitting if the config option is off. However we must pass the vma down in order to know the anon_vma lock to wait for. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: add pmd mangling generic functionsAndrea Arcangeli2011-01-132-1/+124
| | | | | | | | | | | Some are needed to build but not actually used on archs not supporting transparent hugepages. Others like pmdp_clear_flush are used by x86 too. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: CONFIG_TRANSPARENT_HUGEPAGEAndrea Arcangeli2011-01-131-0/+14
| | | | | | | | | | Add config option. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: comment reminder in destroy_compound_pageAndrea Arcangeli2011-01-131-0/+1
| | | | | | | | | | | Warn destroy_compound_page that __split_huge_page_refcount is heavily dependent on its internal behavior. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: export maybe_mkwriteAndrea Arcangeli2011-01-131-13/+0
| | | | | | | | | | | huge_memory.c needs it too when it fallbacks in copying hugepages into regular fragmented pages if hugepage allocation fails during COW. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: clear compound mappingAndrea Arcangeli2011-01-131-7/+4
| | | | | | | | | | | | | | Clear compound mapping for anonymous compound pages like it already happens for regular anonymous pages. But crash if mapping is set for any tail page, also the PageAnon check is meaningless for tail pages. This check only makes sense for the head page, for tail page it can only hide bugs and we definitely don't want to hide bugs. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: put_page: recheck PageHead after releasing the compound_lockAndrea Arcangeli2011-01-131-2/+6
| | | | | | | | | After releasing the compound_lock split_huge_page can still run and release the page before put_page_testzero runs. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: alter compound get_page/put_pageAndrea Arcangeli2011-01-131-7/+83
| | | | | | | | | | | | Alter compound get_page/put_page to keep references on subpages too, in order to allow __split_huge_page_refcount to split an hugepage even while subpages have been pinned by one of the get_user_pages() variants. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: fix bad_page to show the real reason the page is badAndrea Arcangeli2011-01-131-1/+1
| | | | | | | | | | | | page_count shows the count of the head page, but the actual check is done on the tail page, so show what is really being checked. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: ksm: free swap when swapcache page is replacedHugh Dickins2011-01-131-0/+2
| | | | | | | | | | | When a swapcache page is replaced by a ksm page, it's best to free that swap immediately. Reported-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* writeback: avoid unnecessary determine_dirtyable_memory callMinchan Kim2011-01-131-1/+4
| | | | | | | | | | | | | | | | | | | | | I think determine_dirtyable_memory() is a rather costly function since it need many atomic reads for gathering zone/global page state. But when we use vm_dirty_bytes && dirty_background_bytes, we don't need that costly calculation. This patch eliminates such unnecessary overhead. NOTE : newly added if condition might add overhead in normal path. But it should be _really_ small because anyway we need the access both vm_dirty_bytes and dirty_background_bytes so it is likely to hit the cache. [akpm@linux-foundation.org: fix used-uninitialised warning] Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: set correct numa_zonelist_order string when configured on the kernel ↵Volodymyr G. Lukiianyk2011-01-131-3/+10
| | | | | | | | | | | | | | | command line When numa_zonelist_order parameter is set to "node" or "zone" on the command line it's still showing as "default" in sysctl. That's because early_param parsing function changes only user_zonelist_order variable. Fix this by copying user-provided string to numa_zonelist_order if it was successfully parsed. Signed-off-by: Volodymyr G Lukiianyk <volodymyrgl@gmail.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: kswapd: use the classzone idx that kswapd was using for ↵Mel Gorman2011-01-131-13/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | sleeping_prematurely() When kswapd is woken up for a high-order allocation, it takes account of the highest usable zone by the caller (the classzone idx). During allocation, this index is used to select the lowmem_reserve[] that should be applied to the watermark calculation in zone_watermark_ok(). When balancing a node, kswapd considers the highest unbalanced zone to be the classzone index. This will always be at least be the callers classzone_idx and can be higher. However, sleeping_prematurely() always considers the lowest zone (e.g. ZONE_DMA) to be the classzone index. This means that sleeping_prematurely() can consider a zone to be balanced that is unusable by the allocation request that originally woke kswapd. This patch changes sleeping_prematurely() to use a classzone_idx matching the value it used in balance_pgdat(). Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: kswapd: treat zone->all_unreclaimable in sleeping_prematurely similar to ↵Mel Gorman2011-01-131-1/+9
| | | | | | | | | | | | | | | | | | | | | balance_pgdat() After DEF_PRIORITY, balance_pgdat() considers all_unreclaimable zones to be balanced but sleeping_prematurely does not. This can force kswapd to stay awake longer than it should. This patch fixes it. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: kswapd: reset kswapd_max_order and classzone_idx after readingMel Gorman2011-01-131-0/+2
| | | | | | | | | | | | | | | | | | | | | | | When kswapd wakes up, it reads its order and classzone from pgdat and calls balance_pgdat. While its awake, it potentially reclaimes at a high order and a low classzone index. This might have been a once-off that was not required by subsequent callers. However, because the pgdat values were not reset, they remain artifically high while balance_pgdat() is running and potentially kswapd enters a second unnecessary reclaim cycle. Reset the pgdat order and classzone index after reading. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: kswapd: use the order that kswapd was reclaiming at for ↵Mel Gorman2011-01-131-5/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | sleeping_prematurely() Before kswapd goes to sleep, it uses sleeping_prematurely() to check if there was a race pushing a zone below its watermark. If the race happened, it stays awake. However, balance_pgdat() can decide to reclaim at order-0 if it decides that high-order reclaim is not working as expected. This information is not passed back to sleeping_prematurely(). The impact is that kswapd remains awake reclaiming pages long after it should have gone to sleep. This patch passes the adjusted order to sleeping_prematurely and uses the same logic as balance_pgdat to decide if it's ok to go to sleep. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: kswapd: keep kswapd awake for high-order allocations until a percentage ↵Mel Gorman2011-01-131-9/+49
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | of the node is balanced When reclaiming for high-orders, kswapd is responsible for balancing a node but it should not reclaim excessively. It avoids excessive reclaim by considering if any zone in a node is balanced then the node is balanced. In the cases where there are imbalanced zone sizes (e.g. ZONE_DMA with both ZONE_DMA32 and ZONE_NORMAL), kswapd can go to sleep prematurely as just one small zone was balanced. This alters the sleep logic of kswapd slightly. It counts the number of pages that make up the balanced zones. If the total number of balanced pages is more than a quarter of the zone, kswapd will go back to sleep. This should keep a node balanced without reclaiming an excessive number of pages. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: kswapd: stop high-order balancing when any suitable zone is balancedMel Gorman2011-01-132-12/+64
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Simon Kirby reported the following problem We're seeing cases on a number of servers where cache never fully grows to use all available memory. Sometimes we see servers with 4 GB of memory that never seem to have less than 1.5 GB free, even with a constantly-active VM. In some cases, these servers also swap out while this happens, even though they are constantly reading the working set into memory. We have been seeing this happening for a long time; I don't think it's anything recent, and it still happens on 2.6.36. After some debugging work by Simon, Dave Hansen and others, the prevaling theory became that kswapd is reclaiming order-3 pages requested by SLUB too aggressive about it. There are two apparent problems here. On the target machine, there is a small Normal zone in comparison to DMA32. As kswapd tries to balance all zones, it would continually try reclaiming for Normal even though DMA32 was balanced enough for callers. The second problem is that sleeping_prematurely() does not use the same logic as balance_pgdat() when deciding whether to sleep or not. This keeps kswapd artifically awake. A number of tests were run and the figures from previous postings will look very different for a few reasons. One, the old figures were forcing my network card to use GFP_ATOMIC in attempt to replicate Simon's problem. Second, I previous specified slub_min_order=3 again in an attempt to reproduce Simon's problem. In this posting, I'm depending on Simon to say whether his problem is fixed or not and these figures are to show the impact to the ordinary cases. Finally, the "vmscan" figures are taken from /proc/vmstat instead of the tracepoints. There is less information but recording is less disruptive. The first test of relevance was postmark with a process running in the background reading a large amount of anonymous memory in blocks. The objective was to vaguely simulate what was happening on Simon's machine and it's memory intensive enough to have kswapd awake. POSTMARK traceonly kanyzone Transactions per second: 156.00 ( 0.00%) 153.00 (-1.96%) Data megabytes read per second: 21.51 ( 0.00%) 21.52 ( 0.05%) Data megabytes written per second: 29.28 ( 0.00%) 29.11 (-0.58%) Files created alone per second: 250.00 ( 0.00%) 416.00 (39.90%) Files create/transact per second: 79.00 ( 0.00%) 76.00 (-3.95%) Files deleted alone per second: 520.00 ( 0.00%) 420.00 (-23.81%) Files delete/transact per second: 79.00 ( 0.00%) 76.00 (-3.95%) MMTests Statistics: duration User/Sys Time Running Test (seconds) 16.58 17.4 Total Elapsed Time (seconds) 218.48 222.47 VMstat Reclaim Statistics: vmscan Direct reclaims 0 4 Direct reclaim pages scanned 0 203 Direct reclaim pages reclaimed 0 184 Kswapd pages scanned 326631 322018 Kswapd pages reclaimed 312632 309784 Kswapd low wmark quickly 1 4 Kswapd high wmark quickly 122 475 Kswapd skip congestion_wait 1 0 Pages activated 700040 705317 Pages deactivated 212113 203922 Pages written 9875 6363 Total pages scanned 326631 322221 Total pages reclaimed 312632 309968 %age total pages scanned/reclaimed 95.71% 96.20% %age total pages scanned/written 3.02% 1.97% proc vmstat: Faults Major Faults 300 254 Minor Faults 645183 660284 Page ins 493588 486704 Page outs 4960088 4986704 Swap ins 1230 661 Swap outs 9869 6355 Performance is mildly affected because kswapd is no longer doing as much work and the background memory consumer process is getting in the way. Note that kswapd scanned and reclaimed fewer pages as it's less aggressive and overall fewer pages were scanned and reclaimed. Swap in/out is particularly reduced again reflecting kswapd throwing out fewer pages. The slight performance impact is unfortunate here but it looks like a direct result of kswapd being less aggressive. As the bug report is about too many pages being freed by kswapd, it may have to be accepted for now. The second test is a streaming IO benchmark that was previously used by Johannes to show regressions in page reclaim. MICRO traceonly kanyzone User/Sys Time Running Test (seconds) 29.29 28.87 Total Elapsed Time (seconds) 492.18 488.79 VMstat Reclaim Statistics: vmscan Direct reclaims 2128 1460 Direct reclaim pages scanned 2284822 1496067 Direct reclaim pages reclaimed 148919 110937 Kswapd pages scanned 15450014 16202876 Kswapd pages reclaimed 8503697 8537897 Kswapd low wmark quickly 3100 3397 Kswapd high wmark quickly 1860 7243 Kswapd skip congestion_wait 708 801 Pages activated 9635 9573 Pages deactivated 1432 1271 Pages written 223 1130 Total pages scanned 17734836 17698943 Total pages reclaimed 8652616 8648834 %age total pages scanned/reclaimed 48.79% 48.87% %age total pages scanned/written 0.00% 0.01% proc vmstat: Faults Major Faults 165 221 Minor Faults 9655785 9656506 Page ins 3880 7228 Page outs 37692940 37480076 Swap ins 0 69 Swap outs 19 15 Again fewer pages are scanned and reclaimed as expected and this time the test completed faster. Note that kswapd is hitting its watermarks faster (low and high wmark quickly) which I expect is due to kswapd reclaiming fewer pages. I also ran fs-mark, iozone and sysbench but there is nothing interesting to report in the figures. Performance is not significantly changed and the reclaim statistics look reasonable. Tgis patch: When the allocator enters its slow path, kswapd is woken up to balance the node. It continues working until all zones within the node are balanced. For order-0 allocations, this makes perfect sense but for higher orders it can have unintended side-effects. If the zone sizes are imbalanced, kswapd may reclaim heavily within a smaller zone discarding an excessive number of pages. The user-visible behaviour is that kswapd is awake and reclaiming even though plenty of pages are free from a suitable zone. This patch alters the "balance" logic for high-order reclaim allowing kswapd to stop if any suitable zone becomes balanced to reduce the number of pages it reclaims from other zones. kswapd still tries to ensure that order-0 watermarks for all zones are met before sleeping. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Eric B Munson <emunson@mgebm.net> Cc: Simon Kirby <sim@hostway.ca> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove likely() from grab_cache_page_write_begin()Steven Rostedt2011-01-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Running the annotated branch profiler on a box doing average work (firefox, evolution, xchat, distcc farm), the likely() used in grab_cache_page_write_begin() was incorrect most of the time: correct incorrect % Function File Line ------- --------- - -------- ---- ---- 1924262 71332401 97 grab_cache_page_write_begin filemap.c 2206 Adding a trace_printk() and running the function tracer limited to just this function I can see: gconfd-2-2696 [000] 4467.268935: grab_cache_page_write_begin: page= (null) mapping=ffff8800676a9460 index=7 gconfd-2-2696 [000] 4467.268946: grab_cache_page_write_begin <-ext3_write_begin gconfd-2-2696 [000] 4467.268947: grab_cache_page_write_begin: page= (null) mapping=ffff8800676a9460 index=8 gconfd-2-2696 [000] 4467.268959: grab_cache_page_write_begin <-ext3_write_begin gconfd-2-2696 [000] 4467.268960: grab_cache_page_write_begin: page= (null) mapping=ffff8800676a9460 index=9 gconfd-2-2696 [000] 4467.268972: grab_cache_page_write_begin <-ext3_write_begin gconfd-2-2696 [000] 4467.268973: grab_cache_page_write_begin: page= (null) mapping=ffff8800676a9460 index=10 gconfd-2-2696 [000] 4467.268991: grab_cache_page_write_begin <-ext3_write_begin gconfd-2-2696 [000] 4467.268992: grab_cache_page_write_begin: page= (null) mapping=ffff8800676a9460 index=11 gconfd-2-2696 [000] 4467.269005: grab_cache_page_write_begin <-ext3_write_begin Which shows that a lot of calls from ext3_write_begin will result in the page returned by "find_lock_page" will be NULL. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* vmalloc: remove redundant unlikely()Tobias Klauser2011-01-131-1/+1
| | | | | | | | | IS_ERR() already implies unlikely(), so it can be omitted here. Signed-off-by: Tobias Klauser <tklauser@distanz.ch> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mempolicy: remove tasklist_lock from migrate_pagesKOSAKI Motohiro2011-01-131-3/+0
| | | | | | | | | | | Today, tasklist_lock in migrate_pages doesn't protect anything. rcu_read_lock() provide enough protection from pid hash walk. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reported-by: Peter Zijlstra <peterz@infradead.org> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mlock: do not hold mmap_sem for extended periods of timeMichel Lespinasse2011-01-134-25/+47
| | | | | | | | | | | | | | | | | | | | | __get_user_pages gets a new 'nonblocking' parameter to signal that the caller is prepared to re-acquire mmap_sem and retry the operation if needed. This is used to split off long operations if they are going to block on a disk transfer, or when we detect contention on the mmap_sem. [akpm@linux-foundation.org: remove ref to rwsem_is_contended()] Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: move VM_LOCKED check to __mlock_vma_pages_range()Michel Lespinasse2011-01-131-13/+13
| | | | | | | | | | | | | | | | | | | | | Use a single code path for faulting in pages during mlock. The reason to have it in this patch series is that I did not want to update both code paths in a later change that releases mmap_sem when blocking on disk. Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add FOLL_MLOCK follow_page flag.Michel Lespinasse2011-01-132-60/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | Move the code to mlock pages from __mlock_vma_pages_range() to follow_page(). This allows __mlock_vma_pages_range() to not have to break down work into 16-page batches. An additional motivation for doing this within the present patch series is that it'll make it easier for a later chagne to drop mmap_sem when blocking on disk (we'd like to be able to resume at the page that was read from disk instead of at the start of a 16-page batch). Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mlock: only hold mmap_sem in shared mode when faulting in pagesMichel Lespinasse2011-01-131-17/+64
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently mlock() holds mmap_sem in exclusive mode while the pages get faulted in. In the case of a large mlock, this can potentially take a very long time, during which various commands such as 'ps auxw' will block. This makes sysadmins unhappy: real 14m36.232s user 0m0.003s sys 0m0.015s (output from 'time ps auxw' while a 20GB file was being mlocked without being previously preloaded into page cache) I propose that mlock() could release mmap_sem after the VM_LOCKED bits have been set in all appropriate VMAs. Then a second pass could be done to actually mlock the pages, in small batches, releasing mmap_sem when we block on disk access or when we detect some contention. This patch: Before this change, mlock() holds mmap_sem in exclusive mode while the pages get faulted in. In the case of a large mlock, this can potentially take a very long time. Various things will block while mmap_sem is held, including 'ps auxw'. This can make sysadmins angry. I propose that mlock() could release mmap_sem after the VM_LOCKED bits have been set in all appropriate VMAs. Then a second pass could be done to actually mlock the pages with mmap_sem held for reads only. We need to recheck the vma flags after we re-acquire mmap_sem, but this is easy. In the case where a vma has been munlocked before mlock completes, pages that were already marked as PageMlocked() are handled by the munlock() call, and mlock() is careful to not mark new page batches as PageMlocked() after the munlock() call has cleared the VM_LOCKED vma flags. So, the end result will be identical to what'd happen if munlock() had executed after the mlock() call. In a later change, I will allow the second pass to release mmap_sem when blocking on disk accesses or when it is otherwise contended, so that it won't be held for long periods of time even in shared mode. Signed-off-by: Michel Lespinasse <walken@google.com> Tested-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mlock: avoid dirtying pages and triggering writebackMichel Lespinasse2011-01-132-2/+12
| | | | | | | | | | | | | | | | | | | | | | | When faulting in pages for mlock(), we want to break COW for anonymous or file pages within VM_WRITABLE, non-VM_SHARED vmas. However, there is no need to write-fault into VM_SHARED vmas since shared file pages can be mlocked first and dirtied later, when/if they actually get written to. Skipping the write fault is desirable, as we don't want to unnecessarily cause these pages to be dirtied and queued for writeback. Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Theodore Tso <tytso@google.com> Cc: Michael Rubin <mrubin@google.com> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* do_wp_page: clarify dirty_page handlingMichel Lespinasse2011-01-131-34/+38
| | | | | | | | | | | | | | | | | | | | Reorganize the code so that dirty pages are handled closer to the place that makes them dirty (handling write fault into shared, writable VMAs). No behavior changes. Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Theodore Tso <tytso@google.com> Cc: Michael Rubin <mrubin@google.com> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* do_wp_page: remove the 'reuse' flagMichel Lespinasse2011-01-131-6/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | mlocking a shared, writable vma currently causes the corresponding pages to be marked as dirty and queued for writeback. This seems rather unnecessary given that the pages are not being actually modified during mlock. It is understood that for non-shared mappings (file or anon) we want to use a write fault in order to break COW, but there is just no such need for shared mappings. The first two patches in this series do not introduce any behavior change. The intent there is to make it obvious that dirtying file pages is only done in the (writable, shared) case. I think this clarifies the code, but I wouldn't mind dropping these two patches if there is no consensus about them. The last patch is where we actually avoid dirtying shared mappings during mlock. Note that as a side effect of this, we won't call page_mkwrite() for the mappings that define it, and won't be pre-allocating data blocks at the FS level if the mapped file was sparsely allocated. My understanding is that mlock does not need to provide such guarantee, as evidenced by the fact that it never did for the filesystems that don't define page_mkwrite() - including some common ones like ext3. However, I would like to gather feedback on this from filesystem people as a precaution. If this turns out to be a showstopper, maybe block preallocation can be added back on using a different interface. Large shared mlocks are getting significantly (>2x) faster in my tests, as the disk can be fully used for reading the file instead of having to share between this and writeback. This patch: Reorganize the code to remove the 'reuse' flag. No behavior changes. Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Theodore Tso <tytso@google.com> Cc: Michael Rubin <mrubin@google.com> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: clear PageError bit in msync & fsyncRik van Riel2011-01-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Temporary IO failures, eg. due to loss of both multipath paths, can permanently leave the PageError bit set on a page, resulting in msync or fsync returning -EIO over and over again, even if IO is now getting to the disk correctly. We already clear the AS_ENOSPC and AS_IO bits in mapping->flags in the filemap_fdatawait_range function. Also clearing the PageError bit on the page allows subsequent msync or fsync calls on this file to return without an error, if the subsequent IO succeeds. Unfortunately data written out in the msync or fsync call that returned -EIO can still get lost, because the page dirty bit appears to not get restored on IO error. However, the alternative could be potentially all of memory filling up with uncleanable dirty pages, hanging the system, so there is no nice choice here... Signed-off-by: Rik van Riel <riel@redhat.com> Acked-by: Valerie Aurora <vaurora@redhat.com> Acked-by: Jeff Layton <jlayton@redhat.com> Cc: Theodore Ts'o <tytso@mit.edu> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: unify module_alloc code for vmallocDavid Rientjes2011-01-131-21/+29
| | | | | | | | | | | | | | | | | | | | | | | Four architectures (arm, mips, sparc, x86) use __vmalloc_area() for module_init(). Much of the code is duplicated and can be generalized in a globally accessible function, __vmalloc_node_range(). __vmalloc_node() now calls into __vmalloc_node_range() with a range of [VMALLOC_START, VMALLOC_END) for functionally equivalent behavior. Each architecture may then use __vmalloc_node_range() directly to remove the duplication of code. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove gfp mask from pcpu_get_vm_areasDavid Rientjes2011-01-132-13/+10
| | | | | | | | | | | pcpu_get_vm_areas() only uses GFP_KERNEL allocations, so remove the gfp_t formal and use the mask internally. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove unused get_vm_area_nodeDavid Rientjes2011-01-131-7/+0
| | | | | | | | | get_vm_area_node() is unused in the kernel and can thus be removed. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: vmscan: rename lumpy_mode to reclaim_modeMel Gorman2011-01-131-35/+35
| | | | | | | | | | | | | | | With compaction being used instead of lumpy reclaim, the name lumpy_mode and associated variables is a bit misleading. Rename lumpy_mode to reclaim_mode which is a better fit. There is no functional change. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: compaction: perform a faster migration scan when migrating asynchronouslyMel Gorman2011-01-131-0/+15
| | | | | | | | | | | | | | | | | | | | | try_to_compact_pages() is initially called to only migrate pages asychronously and kswapd always compacts asynchronously. Both are being optimistic so it is important to complete the work as quickly as possible to minimise stalls. This patch alters the scanner when asynchronous to only consider MIGRATE_MOVABLE pageblocks as migration candidates. This reduces stalls when allocating huge pages while not impairing allocation success rates as a full scan will be performed if necessary after direct reclaim. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: migration: cleanup migrate_pages API by matching types for offlining and ↵Mel Gorman2011-01-134-8/+10
| | | | | | | | | | | | | | | | | sync With the introduction of the boolean sync parameter, the API looks a little inconsistent as offlining is still an int. Convert offlining to a bool for the sake of being tidy. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: migration: allow migration to operate asynchronously and avoid ↵Mel Gorman2011-01-137-26/+49
| | | | | | | | | | | | | | | | | | | | | | | | | synchronous compaction in the faster path Migration synchronously waits for writeback if the initial passes fails. Callers of memory compaction do not necessarily want this behaviour if the caller is latency sensitive or expects that synchronous migration is not going to have a significantly better success rate. This patch adds a sync parameter to migrate_pages() allowing the caller to indicate if wait_on_page_writeback() is allowed within migration or not. For reclaim/compaction, try_to_compact_pages() is first called asynchronously, direct reclaim runs and then try_to_compact_pages() is called synchronously as there is a greater expectation that it'll succeed. [akpm@linux-foundation.org: build/merge fix] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: vmscan: reclaim order-0 and use compaction instead of lumpy reclaimMel Gorman2011-01-134-49/+175
| | | | | | | | | | | | | | | | | | | | | | | | | | Lumpy reclaim is disruptive. It reclaims a large number of pages and ignores the age of the pages it reclaims. This can incur significant stalls and potentially increase the number of major faults. Compaction has reached the point where it is considered reasonably stable (meaning it has passed a lot of testing) and is a potential candidate for displacing lumpy reclaim. This patch introduces an alternative to lumpy reclaim whe compaction is available called reclaim/compaction. The basic operation is very simple - instead of selecting a contiguous range of pages to reclaim, a number of order-0 pages are reclaimed and then compaction is later by either kswapd (compact_zone_order()) or direct compaction (__alloc_pages_direct_compact()). [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: use conventional task_struct naming] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: vmscan: convert lumpy_mode into a bitmaskMel Gorman2011-01-131-18/+28
| | | | | | | | | | | | | | | Currently lumpy_mode is an enum and determines if lumpy reclaim is off, syncronous or asyncronous. In preparation for using compaction instead of lumpy reclaim, this patch converts the flags into a bitmap. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: compaction: add trace events for memory compaction activityMel Gorman2011-01-131-1/+13
| | | | | | | | | | | | | | | | | In preparation for a patches promoting the use of memory compaction over lumpy reclaim, this patch adds trace points for memory compaction activity. Using them, we can monitor the scanning activity of the migration and free page scanners as well as the number and success rates of pages passed to page migration. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: convert sprintf_symbol to %pSJoe Perches2011-01-132-14/+6
| | | | | | | | Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Pekka Enberg <penberg@kernel.org> Cc: Jiri Kosina <trivial@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: find_get_pages_contig fixletNick Piggin2011-01-131-3/+10
| | | | | | | | | | | Testing ->mapping and ->index without a ref is not stable as the page may have been reused at this point. Signed-off-by: Nick Piggin <npiggin@kernel.dk> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* vmscan: factor out kswapd sleeping logic from kswapd()KOSAKI Motohiro2011-01-131-46/+46
| | | | | | | | | | Currently, kswapd() has deep nesting and is slightly hard to read. Clean this up. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/page-writeback.c: fix __set_page_dirty_no_writeback() return valueBob Liu2011-01-131-1/+1
| | | | | | | | | | | __set_page_dirty_no_writeback() should return true if it actually transitioned the page from a clean to dirty state although it seems nobody uses its return value at present. Signed-off-by: Bob Liu <lliubbo@gmail.com> Acked-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: vmstat: use a single setter function and callback for adjusting percpu ↵Mel Gorman2011-01-132-31/+24
| | | | | | | | | | | | | | | | | | | thresholds reduce_pgdat_percpu_threshold() and restore_pgdat_percpu_threshold() exist to adjust the per-cpu vmstat thresholds while kswapd is awake to avoid errors due to counter drift. The functions duplicate some code so this patch replaces them with a single set_pgdat_percpu_threshold() that takes a callback function to calculate the desired threshold as a parameter. [akpm@linux-foundation.org: readability tweak] [kosaki.motohiro@jp.fujitsu.com: set_pgdat_percpu_threshold(): don't use for_each_online_cpu] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Christoph Lameter <cl@linux.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: page allocator: adjust the per-cpu counter threshold when memory is lowMel Gorman2011-01-134-40/+107
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit aa45484 ("calculate a better estimate of NR_FREE_PAGES when memory is low") noted that watermarks were based on the vmstat NR_FREE_PAGES. To avoid synchronization overhead, these counters are maintained on a per-cpu basis and drained both periodically and when a threshold is above a threshold. On large CPU systems, the difference between the estimate and real value of NR_FREE_PAGES can be very high. The system can get into a case where pages are allocated far below the min watermark potentially causing livelock issues. The commit solved the problem by taking a better reading of NR_FREE_PAGES when memory was low. Unfortately, as reported by Shaohua Li this accurate reading can consume a large amount of CPU time on systems with many sockets due to cache line bouncing. This patch takes a different approach. For large machines where counter drift might be unsafe and while kswapd is awake, the per-cpu thresholds for the target pgdat are reduced to limit the level of drift to what should be a safe level. This incurs a performance penalty in heavy memory pressure by a factor that depends on the workload and the machine but the machine should function correctly without accidentally exhausting all memory on a node. There is an additional cost when kswapd wakes and sleeps but the event is not expected to be frequent - in Shaohua's test case, there was one recorded sleep and wake event at least. To ensure that kswapd wakes up, a safe version of zone_watermark_ok() is introduced that takes a more accurate reading of NR_FREE_PAGES when called from wakeup_kswapd, when deciding whether it is really safe to go back to sleep in sleeping_prematurely() and when deciding if a zone is really balanced or not in balance_pgdat(). We are still using an expensive function but limiting how often it is called. When the test case is reproduced, the time spent in the watermark functions is reduced. The following report is on the percentage of time spent cumulatively spent in the functions zone_nr_free_pages(), zone_watermark_ok(), __zone_watermark_ok(), zone_watermark_ok_safe(), zone_page_state_snapshot(), zone_page_state(). vanilla 11.6615% disable-threshold 0.2584% David said: : We had to pull aa454840 "mm: page allocator: calculate a better estimate : of NR_FREE_PAGES when memory is low and kswapd is awake" from 2.6.36 : internally because tests showed that it would cause the machine to stall : as the result of heavy kswapd activity. I merged it back with this fix as : it is pending in the -mm tree and it solves the issue we were seeing, so I : definitely think this should be pushed to -stable (and I would seriously : consider it for 2.6.37 inclusion even at this late date). Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reported-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Christoph Lameter <cl@linux.com> Tested-by: Nicolas Bareil <nico@chdir.org> Cc: David Rientjes <rientjes@google.com> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: <stable@kernel.org> [2.6.37.1, 2.6.36.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-blockLinus Torvalds2011-01-131-3/+4
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block: (43 commits) block: ensure that completion error gets properly traced blktrace: add missing probe argument to block_bio_complete block cfq: don't use atomic_t for cfq_group block cfq: don't use atomic_t for cfq_queue block: trace event block fix unassigned field block: add internal hd part table references block: fix accounting bug on cross partition merges kref: add kref_test_and_get bio-integrity: mark kintegrityd_wq highpri and CPU intensive block: make kblockd_workqueue smarter Revert "sd: implement sd_check_events()" block: Clean up exit_io_context() source code. Fix compile warnings due to missing removal of a 'ret' variable fs/block: type signature of major_to_index(int) to major_to_index(unsigned) block: convert !IS_ERR(p) && p to !IS_ERR_NOR_NULL(p) cfq-iosched: don't check cfqg in choose_service_tree() fs/splice: Pull buf->ops->confirm() from splice_from_pipe actors cdrom: export cdrom_check_events() sd: implement sd_check_events() sr: implement sr_check_events() ...
| * Merge branch 'cleanup-bd_claim' of ↵Jens Axboe2010-11-271-3/+4
| |\ | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc into for-2.6.38/core
| | * block: make blkdev_get/put() handle exclusive accessTejun Heo2010-11-131-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Over time, block layer has accumulated a set of APIs dealing with bdev open, close, claim and release. * blkdev_get/put() are the primary open and close functions. * bd_claim/release() deal with exclusive open. * open/close_bdev_exclusive() are combination of open and claim and the other way around, respectively. * bd_link/unlink_disk_holder() to create and remove holder/slave symlinks. * open_by_devnum() wraps bdget() + blkdev_get(). The interface is a bit confusing and the decoupling of open and claim makes it impossible to properly guarantee exclusive access as in-kernel open + claim sequence can disturb the existing exclusive open even before the block layer knows the current open if for another exclusive access. Reorganize the interface such that, * blkdev_get() is extended to include exclusive access management. @holder argument is added and, if is @FMODE_EXCL specified, it will gain exclusive access atomically w.r.t. other exclusive accesses. * blkdev_put() is similarly extended. It now takes @mode argument and if @FMODE_EXCL is set, it releases an exclusive access. Also, when the last exclusive claim is released, the holder/slave symlinks are removed automatically. * bd_claim/release() and close_bdev_exclusive() are no longer necessary and either made static or removed. * bd_link_disk_holder() remains the same but bd_unlink_disk_holder() is no longer necessary and removed. * open_bdev_exclusive() becomes a simple wrapper around lookup_bdev() and blkdev_get(). It also has an unexpected extra bdev_read_only() test which probably should be moved into blkdev_get(). * open_by_devnum() is modified to take @holder argument and pass it to blkdev_get(). Most of bdev open/close operations are unified into blkdev_get/put() and most exclusive accesses are tested atomically at the open time (as it should). This cleans up code and removes some, both valid and invalid, but unnecessary all the same, corner cases. open_bdev_exclusive() and open_by_devnum() can use further cleanup - rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop special features. Well, let's leave them for another day. Most conversions are straight-forward. drbd conversion is a bit more involved as there was some reordering, but the logic should stay the same. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Brown <neilb@suse.de> Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Acked-by: Mike Snitzer <snitzer@redhat.com> Acked-by: Philipp Reisner <philipp.reisner@linbit.com> Cc: Peter Osterlund <petero2@telia.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Jan Kara <jack@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <joel.becker@oracle.com> Cc: Alex Elder <aelder@sgi.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: dm-devel@redhat.com Cc: drbd-dev@lists.linbit.com Cc: Leo Chen <leochen@broadcom.com> Cc: Scott Branden <sbranden@broadcom.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Cc: Joern Engel <joern@logfs.org> Cc: reiserfs-devel@vger.kernel.org Cc: Alexander Viro <viro@zeniv.linux.org.uk>
* | | Merge branch 'for-next' of ↵Linus Torvalds2011-01-135-5/+5
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial * 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (43 commits) Documentation/trace/events.txt: Remove obsolete sched_signal_send. writeback: fix global_dirty_limits comment runtime -> real-time ppc: fix comment typo singal -> signal drivers: fix comment typo diable -> disable. m68k: fix comment typo diable -> disable. wireless: comment typo fix diable -> disable. media: comment typo fix diable -> disable. remove doc for obsolete dynamic-printk kernel-parameter remove extraneous 'is' from Documentation/iostats.txt Fix spelling milisec -> ms in snd_ps3 module parameter description Fix spelling mistakes in comments Revert conflicting V4L changes i7core_edac: fix typos in comments mm/rmap.c: fix comment sound, ca0106: Fix assignment to 'channel'. hrtimer: fix a typo in comment init/Kconfig: fix typo anon_inodes: fix wrong function name in comment fix comment typos concerning "consistent" poll: fix a typo in comment ... Fix up trivial conflicts in: - drivers/net/wireless/iwlwifi/iwl-core.c (moved to iwl-legacy.c) - fs/ext4/ext4.h Also fix missed 'diabled' typo in drivers/net/bnx2x/bnx2x.h while at it.
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