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* mm: add alloc_pages_exact() and free_pages_exact()Timur Tabi2008-07-241-0/+3
| | | | | | | | | | | | | | | | | alloc_pages_exact() is similar to alloc_pages(), except that it allocates the minimum number of pages to fulfill the request. This is useful if you want to allocate a very large buffer that is slightly larger than an even power-of-two number of pages. In that case, alloc_pages() will waste a lot of memory. I have a video driver that wants to allocate a 5MB buffer. alloc_pages() wiill waste 3MB of physically-contiguous memory. Signed-off-by: Timur Tabi <timur@freescale.com> Cc: Andi Kleen <andi@firstfloor.org> 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>
* bootmem: replace node_boot_start in struct bootmem_dataJohannes Weiner2008-07-241-1/+1
| | | | | | | | | | | | Almost all users of this field need a PFN instead of a physical address, so replace node_boot_start with node_min_pfn. [Lee.Schermerhorn@hp.com: fix spurious BUG_ON() in mark_bootmem()] Signed-off-by: Johannes Weiner <hannes@saeureba.de> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: clean up alloc_bootmem_coreJohannes Weiner2008-07-241-4/+2
| | | | | | | | | | | | | | | | | | | | | | alloc_bootmem_core has become quite nasty to read over time. This is a clean rewrite that keeps the semantics. bdata->last_pos has been dropped. bdata->last_success has been renamed to hint_idx and it is now an index relative to the node's range. Since further block searching might start at this index, it is now set to the end of a succeeded allocation rather than its beginning. bdata->last_offset has been renamed to last_end_off to be more clear that it represents the ending address of the last allocation relative to the node. [y-goto@jp.fujitsu.com: fix new alloc_bootmem_core()] Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: reorder code to match new bootmem structureJohannes Weiner2008-07-241-41/+45
| | | | | | | | | This only reorders functions so that further patches will be easier to read. No code changed. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* powerpc: support multiple hugepage sizesJon Tollefson2008-07-244-6/+8
| | | | | | | | | | | | | | | | | | Instead of using the variable mmu_huge_psize to keep track of the huge page size we use an array of MMU_PAGE_* values. For each supported huge page size we need to know the hugepte_shift value and have a pgtable_cache. The hstate or an mmu_huge_psizes index is passed to functions so that they know which huge page size they should use. The hugepage sizes 16M and 64K are setup(if available on the hardware) so that they don't have to be set on the boot cmd line in order to use them. The number of 16G pages have to be specified at boot-time though (e.g. hugepagesz=16G hugepages=5). Signed-off-by: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* powerpc: define support for 16G hugepagesJon Tollefson2008-07-241-1/+1
| | | | | | | | | | | | | | | | The huge page size is defined for 16G pages. If a hugepagesz of 16G is specified at boot-time then it becomes the huge page size instead of the default 16M. The change in pgtable-64K.h is to the macro pte_iterate_hashed_subpages to make the increment to va (the 1 being shifted) be a long so that it is not shifted to 0. Otherwise it would create an infinite loop when the shift value is for a 16G page (when base page size is 64K). Signed-off-by: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* powerpc: scan device tree for gigantic pagesJon Tollefson2008-07-241-0/+2
| | | | | | | | | | | | | The 16G huge pages have to be reserved in the HMC prior to boot. The location of the pages are placed in the device tree. This patch adds code to scan the device tree during very early boot and save these page locations until hugetlbfs is ready for them. Acked-by: Adam Litke <agl@us.ibm.com> Signed-off-by: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: allow arch overridden hugepage allocationJon Tollefson2008-07-241-0/+10
| | | | | | | | | | | | | | | Allow alloc_bootmem_huge_page() to be overridden by architectures that can't always use bootmem. This requires huge_boot_pages to be available for use by this function. This is required for powerpc 16G pages, which have to be reserved prior to boot-time. The location of these pages are indicated in the device tree. Acked-by: Adam Litke <agl@us.ibm.com> Signed-off-by: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* x86: add hugepagesz option on 64-bitAndi Kleen2008-07-241-0/+2
| | | | | | | | | | | | Add an hugepagesz=... option similar to IA64, PPC etc. to x86-64. This finally allows to select GB pages for hugetlbfs in x86 now that all the infrastructure is in place. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: introduce pud_hugeAndi Kleen2008-07-241-0/+5
| | | | | | | | | | | | Straight forward extensions for huge pages located in the PUD instead of PMDs. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce non panic alloc_bootmemAndi Kleen2008-07-241-0/+4
| | | | | | | | | | | Straight forward variant of the existing __alloc_bootmem_node, only subsequent patch when allocating giant hugepages at boot -- don't want to panic if we can't allocate as many as the user asked for. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: new sysfs interfaceNishanth Aravamudan2008-07-241-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlbfs: per mount huge page sizesAndi Kleen2008-07-241-5/+9
| | | | | | | | | | | | | | | | | | | | | | Add the ability to configure the hugetlb hstate used on a per mount basis. - Add a new pagesize= option to the hugetlbfs mount that allows setting the page size - This option causes the mount code to find the hstate corresponding to the specified size, and sets up a pointer to the hstate in the mount's superblock. - Change the hstate accessors to use this information rather than the global_hstate they were using (requires a slight change in mm/memory.c so we don't NULL deref in the error-unmap path -- see comments). [np: take hstate out of hugetlbfs inode and vma->vm_private_data] Acked-by: Adam Litke <agl@us.ibm.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: multiple hstates for multiple page sizesAndi Kleen2008-07-241-3/+16
| | | | | | | | | | | | | | | | | Add basic support for more than one hstate in hugetlbfs. This is the key to supporting multiple hugetlbfs page sizes at once. - Rather than a single hstate, we now have an array, with an iterator - default_hstate continues to be the struct hstate which we use by default - Add functions for architectures to register new hstates [akpm@linux-foundation.org: coding-style fixes] Acked-by: Adam Litke <agl@us.ibm.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: modular state for hugetlb page sizeAndi Kleen2008-07-247-13/+98
| | | | | | | | | | | | | | | | | | | | | | | | | | The goal of this patchset is to support multiple hugetlb page sizes. This is achieved by introducing a new struct hstate structure, which encapsulates the important hugetlb state and constants (eg. huge page size, number of huge pages currently allocated, etc). The hstate structure is then passed around the code which requires these fields, they will do the right thing regardless of the exact hstate they are operating on. This patch adds the hstate structure, with a single global instance of it (default_hstate), and does the basic work of converting hugetlb to use the hstate. Future patches will add more hstate structures to allow for different hugetlbfs mounts to have different page sizes. [akpm@linux-foundation.org: coding-style fixes] Acked-by: Adam Litke <agl@us.ibm.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: create /sys/kernel/mmNishanth Aravamudan2008-07-241-0/+2
| | | | | | | | | | | | | | | Add a kobject to create /sys/kernel/mm when sysfs is mounted. The kobject will exist regardless. This will allow for the hugepage related sysfs directories to exist under the mm "subsystem" directory. Add an ABI file appropriately. [kosaki.motohiro@jp.fujitsu.com: fix build] Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Mel Gorman <mel@csn.ul.ie> 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: record MAP_NORESERVE status on vmas and fix small page mprotect reservationsAndy Whitcroft2008-07-241-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With Mel's hugetlb private reservation support patches applied, strict overcommit semantics are applied to both shared and private huge page mappings. This can be a problem if an application relied on unlimited overcommit semantics for private mappings. An example of this would be an application which maps a huge area with the intention of using it very sparsely. These application would benefit from being able to opt-out of the strict overcommit. It should be noted that prior to hugetlb supporting demand faulting all mappings were fully populated and so applications of this type should be rare. This patch stack implements the MAP_NORESERVE mmap() flag for huge page mappings. This flag has the same meaning as for small page mappings, suppressing reservations for that mapping. Thanks to Mel Gorman for reviewing a number of early versions of these patches. This patch: When a small page mapping is created with mmap() reservations are created by default for any memory pages required. When the region is read/write the reservation is increased for every page, no reservation is needed for read-only regions (as they implicitly share the zero page). Reservations are tracked via the VM_ACCOUNT vma flag which is present when the region has reservation backing it. When we convert a region from read-only to read-write new reservations are aquired and VM_ACCOUNT is set. However, when a read-only map is created with MAP_NORESERVE it is indistinguishable from a normal mapping. When we then convert that to read/write we are forced to incorrectly create reservations for it as we have no record of the original MAP_NORESERVE. This patch introduces a new vma flag VM_NORESERVE which records the presence of the original MAP_NORESERVE flag. This allows us to distinguish these two circumstances and correctly account the reserve. As well as fixing this FIXME in the code, this makes it much easier to introduce MAP_NORESERVE support for huge pages as this flag is available consistantly for the life of the mapping. VM_ACCOUNT on the other hand is heavily used at the generic level in association with small pages. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: guarantee that COW faults for a process that called ↵Mel Gorman2008-07-241-3/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | mmap(MAP_PRIVATE) on hugetlbfs will succeed After patch 2 in this series, a process that successfully calls mmap() for a MAP_PRIVATE mapping will be guaranteed to successfully fault until a process calls fork(). At that point, the next write fault from the parent could fail due to COW if the child still has a reference. We only reserve pages for the parent but a copy must be made to avoid leaking data from the parent to the child after fork(). Reserves could be taken for both parent and child at fork time to guarantee faults but if the mapping is large it is highly likely we will not have sufficient pages for the reservation, and it is common to fork only to exec() immediatly after. A failure here would be very undesirable. Note that the current behaviour of mainline with MAP_PRIVATE pages is pretty bad. The following situation is allowed to occur today. 1. Process calls mmap(MAP_PRIVATE) 2. Process calls mlock() to fault all pages and makes sure it succeeds 3. Process forks() 4. Process writes to MAP_PRIVATE mapping while child still exists 5. If the COW fails at this point, the process gets SIGKILLed even though it had taken care to ensure the pages existed This patch improves the situation by guaranteeing the reliability of the process that successfully calls mmap(). When the parent performs COW, it will try to satisfy the allocation without using reserves. If that fails the parent will steal the page leaving any children without a page. Faults from the child after that point will result in failure. If the child COW happens first, an attempt will be made to allocate the page without reserves and the child will get SIGKILLed on failure. To summarise the new behaviour: 1. If the original mapper performs COW on a private mapping with multiple references, it will attempt to allocate a hugepage from the pool or the buddy allocator without using the existing reserves. On fail, VMAs mapping the same area are traversed and the page being COW'd is unmapped where found. It will then steal the original page as the last mapper in the normal way. 2. The VMAs the pages were unmapped from are flagged to note that pages with data no longer exist. Future no-page faults on those VMAs will terminate the process as otherwise it would appear that data was corrupted. A warning is printed to the console that this situation occured. 2. If the child performs COW first, it will attempt to satisfy the COW from the pool if there are enough pages or via the buddy allocator if overcommit is allowed and the buddy allocator can satisfy the request. If it fails, the child will be killed. If the pool is large enough, existing applications will not notice that the reserves were a factor. Existing applications depending on the no-reserves been set are unlikely to exist as for much of the history of hugetlbfs, pages were prefaulted at mmap(), allocating the pages at that point or failing the mmap(). [npiggin@suse.de: fix CONFIG_HUGETLB=n build] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: reserve huge pages for reliable MAP_PRIVATE hugetlbfs mappings ↵Mel Gorman2008-07-241-1/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | until fork() This patch reserves huge pages at mmap() time for MAP_PRIVATE mappings in a similar manner to the reservations taken for MAP_SHARED mappings. The reserve count is accounted both globally and on a per-VMA basis for private mappings. This guarantees that a process that successfully calls mmap() will successfully fault all pages in the future unless fork() is called. The characteristics of private mappings of hugetlbfs files behaviour after this patch are; 1. The process calling mmap() is guaranteed to succeed all future faults until it forks(). 2. On fork(), the parent may die due to SIGKILL on writes to the private mapping if enough pages are not available for the COW. For reasonably reliable behaviour in the face of a small huge page pool, children of hugepage-aware processes should not reference the mappings; such as might occur when fork()ing to exec(). 3. On fork(), the child VMAs inherit no reserves. Reads on pages already faulted by the parent will succeed. Successful writes will depend on enough huge pages being free in the pool. 4. Quotas of the hugetlbfs mount are checked at reserve time for the mapper and at fault time otherwise. Before this patch, all reads or writes in the child potentially needs page allocations that can later lead to the death of the parent. This applies to reads and writes of uninstantiated pages as well as COW. After the patch it is only a write to an instantiated page that causes problems. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: drop unneeded pgdat argument from free_area_init_node()Johannes Weiner2008-07-241-3/+2
| | | | | | | | | | | | | free_area_init_node() gets passed in the node id as well as the node descriptor. This is redundant as the function can trivially get the node descriptor itself by means of NODE_DATA() and the node's id. I checked all the users and NODE_DATA() seems to be usable everywhere from where this function is called. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mapping_set_error: add unlikely()Andrew Morton2008-07-241-1/+1
| | | | | | | | | This is called on a per-page basis and in the vast majority of cases `error' is zero. Cc: Guillaume Chazarain <guichaz@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* slob: record page flag overlays explicitlyAndy Whitcroft2008-07-241-0/+7
| | | | | | | | | | | | | | | | | | SLOB reuses two page bits for internal purposes, it overlays PG_active and PG_private. This is hidden away in slob.c. Document these overlays explicitly in the main page-flags enum along with all the others. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* slub: record page flag overlays explicitlyAndy Whitcroft2008-07-241-0/+7
| | | | | | | | | | | | | | | | | | SLUB reuses two page bits for internal purposes, it overlays PG_active and PG_error. This is hidden away in slub.c. Document these overlays explicitly in the main page-flags enum along with all the others. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* page-flags: record page flag overlays explicitlyAndy Whitcroft2008-07-241-4/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the recent page flag reorganisation we have a single enum which defines the valid page flags and their values, nice and clear. However there are a number of bits which are overloaded by different subsystems. Firstly there is PG_owner_priv_1 which is used by filesystems and by XEN. Secondly both SLOB and SLUB use a couple of extra page bits to manage internal state for pages they own; both overlay other bits. All of these "aliases" are scattered about the source making it very hard for a reader to know if the bits are safe to rely on in all contexts; confusion here is bad. As we now have a single place where the bits are clearly assigned it makes sense to clarify the reuse of bits by making the aliases explicit and visible with the original bit assignments. This patch creates explicit aliases within the enum itself for the overloaded bits, creates standard bit accessors PageFoo etc. and uses those throughout. This version pulls the bit manipulation out to standard named page bit accessors as suggested by Christoph, it retains the explicit mapping to the overlayed bits. A fusion of both ideas. This has been SLUB and SLOB have been compile tested on x86_64 only, and SLUB boot tested. If people feel this is worth doing then I can run a fuller set of testing. This patch: Some page flags are used for more than one purpose, for example PG_owner_priv_1. Currently there are individual accessors for each user, each built using the common flag name far away from the bit definitions. This makes it hard to see all possible uses of these bits. Now that we have a single enum to generate the bit orders it makes sense to express overlays in the same place. So create per use aliases for this bit in the main page-flags enum and use those in the accessors. [akpm@linux-foundation.org: fix xen] Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fix soft lock up at NFS mount via per-SB LRU-list of unused dentriesKentaro Makita2008-07-241-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [Summary] Split LRU-list of unused dentries to one per superblock to avoid soft lock up during NFS mounts and remounting of any filesystem. Previously I posted here: http://lkml.org/lkml/2008/3/5/590 [Descriptions] - background dentry_unused is a list of dentries which are not referenced. dentry_unused grows up when references on directories or files are released. This list can be very long if there is huge free memory. - the problem When shrink_dcache_sb() is called, it scans all dentry_unused linearly under spin_lock(), and if dentry->d_sb is differnt from given superblock, scan next dentry. This scan costs very much if there are many entries, and very ineffective if there are many superblocks. IOW, When we need to shrink unused dentries on one dentry, but scans unused dentries on all superblocks in the system. For example, we scan 500 dentries to unmount a filesystem, but scans 1,000,000 or more unused dentries on other superblocks. In our case , At mounting NFS*, shrink_dcache_sb() is called to shrink unused dentries on NFS, but scans 100,000,000 unused dentries on superblocks in the system such as local ext3 filesystems. I hear NFS mounting took 1 min on some system in use. * : NFS uses virtual filesystem in rpc layer, so NFS is affected by this problem. 100,000,000 is possible number on large systems. Per-superblock LRU of unused dentried can reduce the cost in reasonable manner. - How to fix I found this problem is solved by David Chinner's "Per-superblock unused dentry LRU lists V3"(1), so I rebase it and add some fix to reclaim with fairness, which is in Andrew Morton's comments(2). 1) http://lkml.org/lkml/2006/5/25/318 2) http://lkml.org/lkml/2006/5/25/320 Split LRU-list of unused dentries to each superblocks. Then, NFS mounting will check dentries under a superblock instead of all. But this spliting will break LRU of dentry-unused. So, I've attempted to make reclaim unused dentrins with fairness by calculate number of dentries to scan on this sb based on following way number of dentries to scan on this sb = count * (number of dentries on this sb / number of dentries in the machine) - ToDo - I have to measuring performance number and do stress tests. - When unmount occurs during prune_dcache(), scanning on same superblock, It is unable to reach next superblock because it is gone away. We restart scannig superblock from first one, it causes unfairness of reclaim unused dentries on first superblock. But I think this happens very rarely. - Test Results Result on 6GB boxes with excessive unused dentries. Without patch: $ cat /proc/sys/fs/dentry-state 10181835 10180203 45 0 0 0 # mount -t nfs 10.124.60.70:/work/kernel-src nfs real 0m1.830s user 0m0.001s sys 0m1.653s With this patch: $ cat /proc/sys/fs/dentry-state 10236610 10234751 45 0 0 0 # mount -t nfs 10.124.60.70:/work/kernel-src nfs real 0m0.106s user 0m0.002s sys 0m0.032s [akpm@linux-foundation.org: fix comments] Signed-off-by: Kentaro Makita <k-makita@np.css.fujitsu.com> Cc: Neil Brown <neilb@suse.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: David Chinner <dgc@sgi.com> Cc: "J. Bruce Fields" <bfields@fieldses.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove double indirection on tlb parameter to free_pgd_range() & CoJan Beulich2008-07-246-8/+6
| | | | | | | | | | | | | | | | | | The double indirection here is not needed anywhere and hence (at least) confusing. Signed-off-by: Jan Beulich <jbeulich@novell.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Acked-by: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* powerpc ioremap_protBenjamin Herrenschmidt2008-07-244-1/+31
| | | | | | | | | | | | | | | | | | | | | | | This adds ioremap_prot and pte_pgprot() so that one can extract protection bits from a PTE and use them to ioremap_prot() (in order to support ptrace of VM_IO | VM_PFNMAP as per Rik's patch). This moves a couple of flag checks around in the ioremap implementations of arch/powerpc. There's a side effect of allowing non-cacheable and non-guarded mappings on ppc32 which before would always have _PAGE_GUARDED set whenever _PAGE_NO_CACHE is. (standard ioremap will still set _PAGE_GUARDED, but ioremap_prot will be capable of setting such a non guarded mapping). Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Dave Airlie <airlied@linux.ie> Cc: Hugh Dickins <hugh@veritas.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* access_process_vm device memory infrastructureRik van Riel2008-07-243-0/+12
| | | | | | | | | | | | | | | | | | | | | | In order to be able to debug things like the X server and programs using the PPC Cell SPUs, the debugger needs to be able to access device memory through ptrace and /proc/pid/mem. This patch: Add the generic_access_phys access function and put the hooks in place to allow access_process_vm to access device or PPC Cell SPU memory. [riel@redhat.com: Add documentation for the vm_ops->access function] Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Benjamin Herrensmidt <benh@kernel.crashing.org> Cc: Dave Airlie <airlied@linux.ie> Cc: Hugh Dickins <hugh@veritas.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnd Bergmann <arnd@arndb.de> Acked-by: 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: remove nopfnNick Piggin2008-07-241-9/+0
| | | | | | | | | | There are no users of nopfn in the tree. Remove it. [hugh@veritas.com: fix build error] Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/vmstat.c: proper externsAdrian Bunk2008-07-241-0/+6
| | | | | | | | | This patch adds proper extern declarations for five variables in include/linux/vmstat.h Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* page allocator: inline some __alloc_pages() wrappersKOSAKI Motohiro2008-07-241-4/+17
| | | | | | | | | | | | Two zonelist patch series rewrote __page_alloc() largely. Now, it is just a wrapper function. Inlining them will save a function call. [akpm@linux-foundation.org: export __alloc_pages_internal] Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Mel Gorman <mel@csn.ul.ie> 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: unexport __alloc_bootmem_core()Johannes Weiner2008-07-241-5/+0
| | | | | | | | | | | | | | | | This function has no external callers, so unexport it. Also fix its naming inconsistency. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Yinghai Lu <yhlu.kernel@gmail.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Mel Gorman <mel@csn.ul.ie> 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: move bootmem descriptors definition to a single placeJohannes Weiner2008-07-241-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | There are a lot of places that define either a single bootmem descriptor or an array of them. Use only one central array with MAX_NUMNODES items instead. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Acked-by: Ralf Baechle <ralf@linux-mips.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Richard Henderson <rth@twiddle.net> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Tony Luck <tony.luck@intel.com> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Kyle McMartin <kyle@parisc-linux.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: David S. Miller <davem@davemloft.net> Cc: Yinghai Lu <yhlu.kernel@gmail.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* add a helper function to test if an object is on the stackFUJITA Tomonori2008-07-241-0/+7
| | | | | | | | | | | | | | | | | | lib/debugobjects.c has a function to test if an object is on the stack. The block layer and ide needs it (they need to avoid DMA from/to stack buffers). This patch moves the function to include/linux/sched.h so that everyone can use it. lib/debugobjects.c uses current->stack but this patch uses a task_stack_page() accessor, which is a preferable way to access the stack. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* move memory_read_from_buffer() from fs.h to string.hAkinobu Mita2008-07-242-2/+3
| | | | | | | | | | | | | | | | | James Bottomley warns that inclusion of linux/fs.h in a low level driver was always a danger signal. This patch moves memory_read_from_buffer() from fs.h to string.h and fixes includes in existing memory_read_from_buffer() users. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: James Bottomley <James.Bottomley@hansenpartnership.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Zhang Rui <rui.zhang@intel.com> Cc: Bob Moore <robert.moore@intel.com> Cc: Thomas Renninger <trenn@suse.de> Cc: Len Brown <lenb@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'sched/for-linus' of ↵Linus Torvalds2008-07-234-5/+23
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: hrtick_enabled() should use cpu_active() sched, x86: clean up hrtick implementation sched: fix build error, provide partition_sched_domains() unconditionally sched: fix warning in inc_rt_tasks() to not declare variable 'rq' if it's not needed cpu hotplug: Make cpu_active_map synchronization dependency clear cpu hotplug, sched: Introduce cpu_active_map and redo sched domain managment (take 2) sched: rework of "prioritize non-migratable tasks over migratable ones" sched: reduce stack size in isolated_cpu_setup() Revert parts of "ftrace: do not trace scheduler functions" Fixed up conflicts in include/asm-x86/thread_info.h (due to the TIF_SINGLESTEP unification vs TIF_HRTICK_RESCHED removal) and kernel/sched_fair.c (due to cpu_active_map vs for_each_cpu_mask_nr() introduction).
| * Merge branch 'sched/urgent' into sched/develIngo Molnar2008-07-201-3/+1
| |\
| | * sched, x86: clean up hrtick implementationPeter Zijlstra2008-07-201-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | random uvesafb failures were reported against Gentoo: http://bugs.gentoo.org/show_bug.cgi?id=222799 and Mihai Moldovan bisected it back to: > 8f4d37ec073c17e2d4aa8851df5837d798606d6f is first bad commit > commit 8f4d37ec073c17e2d4aa8851df5837d798606d6f > Author: Peter Zijlstra <a.p.zijlstra@chello.nl> > Date: Fri Jan 25 21:08:29 2008 +0100 > > sched: high-res preemption tick Linus suspected it to be hrtick + vm86 interaction and observed: > Btw, Peter, Ingo: I think that commit is doing bad things. They aren't > _incorrect_ per se, but they are definitely bad. > > Why? > > Using random _TIF_WORK_MASK flags is really impolite for doing > "scheduling" work. There's a reason that arch/x86/kernel/entry_32.S > special-cases the _TIF_NEED_RESCHED flag: we don't want to exit out of > vm86 mode unnecessarily. > > See the "work_notifysig_v86" label, and how it does that > "save_v86_state()" thing etc etc. Right, I never liked having to fiddle with those TIF flags. Initially I needed it because the hrtimer base lock could not nest in the rq lock. That however is fixed these days. Currently the only reason left to fiddle with the TIF flags is remote wakeups. We cannot program a remote cpu's hrtimer. I've been thinking about using the new and improved IPI function call stuff to implement hrtimer_start_on(). However that does require that smp_call_function_single(.wait=0) works from interrupt context - /me looks at the latest series from Jens - Yes that does seem to be supported, good. Here's a stab at cleaning this stuff up ... Mihai reported test success as well. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Mihai Moldovan <ionic@ionic.de> Cc: Michal Januszewski <spock@gentoo.org> Cc: Antonino Daplas <adaplas@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | sched: fix build error, provide partition_sched_domains() unconditionallyIngo Molnar2008-07-181-1/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | provide an empty partition_sched_domains() definition for the UP case: include/linux/cpuset.h: In function ‘rebuild_sched_domains': include/linux/cpuset.h:163: error: implicit declaration of function ‘partition_sched_domains' Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | cpu hotplug, sched: Introduce cpu_active_map and redo sched domain managment ↵Max Krasnyansky2008-07-182-1/+12
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | (take 2) This is based on Linus' idea of creating cpu_active_map that prevents scheduler load balancer from migrating tasks to the cpu that is going down. It allows us to simplify domain management code and avoid unecessary domain rebuilds during cpu hotplug event handling. Please ignore the cpusets part for now. It needs some more work in order to avoid crazy lock nesting. Although I did simplfy and unify domain reinitialization logic. We now simply call partition_sched_domains() in all the cases. This means that we're using exact same code paths as in cpusets case and hence the test below cover cpusets too. Cpuset changes to make rebuild_sched_domains() callable from various contexts are in the separate patch (right next after this one). This not only boots but also easily handles while true; do make clean; make -j 8; done and while true; do on-off-cpu 1; done at the same time. (on-off-cpu 1 simple does echo 0/1 > /sys/.../cpu1/online thing). Suprisingly the box (dual-core Core2) is quite usable. In fact I'm typing this on right now in gnome-terminal and things are moving just fine. Also this is running with most of the debug features enabled (lockdep, mutex, etc) no BUG_ONs or lockdep complaints so far. I believe I addressed all of the Dmitry's comments for original Linus' version. I changed both fair and rt balancer to mask out non-active cpus. And replaced cpu_is_offline() with !cpu_active() in the main scheduler code where it made sense (to me). Signed-off-by: Max Krasnyanskiy <maxk@qualcomm.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Gregory Haskins <ghaskins@novell.com> Cc: dmitry.adamushko@gmail.com Cc: pj@sgi.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | Merge branch 'cpus4096-for-linus' of ↵Linus Torvalds2008-07-233-40/+130
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'cpus4096-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (31 commits) NR_CPUS: Replace NR_CPUS in speedstep-centrino.c cpumask: Provide a generic set of CPUMASK_ALLOC macros, FIXUP NR_CPUS: Replace NR_CPUS in cpufreq userspace routines NR_CPUS: Replace per_cpu(..., smp_processor_id()) with __get_cpu_var NR_CPUS: Replace NR_CPUS in arch/x86/kernel/genapic_flat_64.c NR_CPUS: Replace NR_CPUS in arch/x86/kernel/genx2apic_uv_x.c NR_CPUS: Replace NR_CPUS in arch/x86/kernel/cpu/proc.c NR_CPUS: Replace NR_CPUS in arch/x86/kernel/cpu/mcheck/mce_64.c cpumask: Optimize cpumask_of_cpu in lib/smp_processor_id.c, fix cpumask: Use optimized CPUMASK_ALLOC macros in the centrino_target cpumask: Provide a generic set of CPUMASK_ALLOC macros cpumask: Optimize cpumask_of_cpu in lib/smp_processor_id.c cpumask: Optimize cpumask_of_cpu in kernel/time/tick-common.c cpumask: Optimize cpumask_of_cpu in drivers/misc/sgi-xp/xpc_main.c cpumask: Optimize cpumask_of_cpu in arch/x86/kernel/ldt.c cpumask: Optimize cpumask_of_cpu in arch/x86/kernel/io_apic_64.c cpumask: Replace cpumask_of_cpu with cpumask_of_cpu_ptr Revert "cpumask: introduce new APIs" cpumask: make for_each_cpu_mask a bit smaller net: Pass reference to cpumask variable in net/sunrpc/svc.c ... Fix up trivial conflicts in drivers/cpufreq/cpufreq.c manually
| * \ Merge branch 'linus' into cpus4096-for-linusIngo Molnar2008-07-21192-2072/+4704
| |\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | Conflicts: net/sunrpc/svc.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | cpumask: Provide a generic set of CPUMASK_ALLOC macros, FIXUPMike Travis2008-07-201-7/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Rename CPUMASK_VAR --> CPUMASK_PTR (and simplify) * Fix a semantic error in CPUMASK_ALLOC * Add a bit of commentry to cpumask.h Signed-off-by: Mike Travis <travis@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | NR_CPUS: Replace per_cpu(..., smp_processor_id()) with __get_cpu_varMike Travis2008-07-201-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | * Slight optimization when getting one's own cpu_info percpu data. Signed-off-by: Mike Travis <travis@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | cpumask: Provide a generic set of CPUMASK_ALLOC macrosMike Travis2008-07-181-0/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Provide a generic set of CPUMASK_ALLOC macros patterned after the SCHED_CPUMASK_ALLOC macros. This is used where multiple cpumask_t variables are declared on the stack to reduce the amount of stack space required. Signed-off-by: Mike Travis <travis@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | cpumask: Replace cpumask_of_cpu with cpumask_of_cpu_ptrMike Travis2008-07-181-5/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * This patch replaces the dangerous lvalue version of cpumask_of_cpu with new cpumask_of_cpu_ptr macros. These are patterned after the node_to_cpumask_ptr macros. In general terms, if there is a cpumask_of_cpu_map[] then a pointer to the cpumask_of_cpu_map[cpu] entry is used. The cpumask_of_cpu_map is provided when there is a large NR_CPUS count, reducing greatly the amount of code generated and stack space used for cpumask_of_cpu(). The pointer to the cpumask_t value is needed for calling set_cpus_allowed_ptr() to reduce the amount of stack space needed to pass the cpumask_t value. If there isn't a cpumask_of_cpu_map[], then a temporary variable is declared and filled in with value from cpumask_of_cpu(cpu) as well as a pointer variable pointing to this temporary variable. Afterwards, the pointer is used to reference the cpumask value. The compiler will optimize out the extra dereference through the pointer as well as the stack space used for the pointer, resulting in identical code. A good example of the orthogonal usages is in net/sunrpc/svc.c: case SVC_POOL_PERCPU: { unsigned int cpu = m->pool_to[pidx]; cpumask_of_cpu_ptr(cpumask, cpu); *oldmask = current->cpus_allowed; set_cpus_allowed_ptr(current, cpumask); return 1; } case SVC_POOL_PERNODE: { unsigned int node = m->pool_to[pidx]; node_to_cpumask_ptr(nodecpumask, node); *oldmask = current->cpus_allowed; set_cpus_allowed_ptr(current, nodecpumask); return 1; } Signed-off-by: Mike Travis <travis@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | Merge branch 'linus' into cpus4096Ingo Molnar2008-07-18254-19098/+3391
| |\ \ \ | | | |/ | | |/| | | | | | | | | | | | | | | | | | | | | Conflicts: drivers/acpi/processor_throttling.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | Merge branch 'linus' into cpus4096Ingo Molnar2008-07-16450-5575/+18791
| |\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Conflicts: arch/x86/xen/smp.c kernel/sched_rt.c net/iucv/iucv.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | | Revert "cpumask: introduce new APIs"Ingo Molnar2008-07-061-4/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This reverts commit acb7669c125676e63cf96582455509216c39745e. the wrappers are not needed anymore. Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | | Merge commit 'v2.6.26-rc9' into cpus4096Ingo Molnar2008-07-06174-400/+871
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