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* CFQ: add think time check for groupShaohua Li2011-07-121-2/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently when the last queue of a group has no request, we don't expire the queue to hope request from the group comes soon, so the group doesn't miss its share. But if the think time is big, the assumption isn't correct and we just waste bandwidth. In such case, we don't do idle. [global] runtime=30 direct=1 [test1] cgroup=test1 cgroup_weight=1000 rw=randread ioengine=libaio size=500m runtime=30 directory=/mnt filename=file1 thinktime=9000 [test2] cgroup=test2 cgroup_weight=1000 rw=randread ioengine=libaio size=500m runtime=30 directory=/mnt filename=file2 patched base test1 64k 39k test2 548k 540k total 604k 578k group1 gets much better throughput because it waits less time. To check if the patch changes behavior of queue without think time. I also tried to give test1 2ms think time or no think time. The test result is stable. The thoughput doesn't change with/without the patch. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* CFQ: add think time check for service treeShaohua Li2011-07-121-4/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently when the last queue of a service tree has no request, we don't expire the queue to hope request from the service tree comes soon, so the service tree doesn't miss its share. But if the think time is big, the assumption isn't correct and we just waste bandwidth. In such case, we don't do idle. [global] runtime=10 direct=1 [test1] rw=randread ioengine=libaio size=500m directory=/mnt filename=file1 thinktime=9000 [test2] rw=read ioengine=libaio size=1G directory=/mnt filename=file2 patched base test1 41k/s 33k/s test2 15868k/s 15789k/s total 15902k/s 15817k/s A slightly better To check if the patch changes behavior of queue without think time. I also tried to give test1 2ms think time or no think time. The test has variation even without the patch, but the average throughput doesn't change with/without the patch. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* CFQ: move think time check variables to a separate structShaohua Li2011-07-121-16/+24
| | | | | | | | | | Move the variables to do think time check to a sepatate struct. This is to prepare adding think time check for service tree and group. No functional change. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* fixlet: Remove fs_excl from struct task.Justin TerAvest2011-07-121-27/+1
| | | | | | | | | | | | | | | | | fs_excl is a poor man's priority inheritance for filesystems to hint to the block layer that an operation is important. It was never clearly specified, not widely adopted, and will not prevent starvation in many cases (like across cgroups). fs_excl was introduced with the time sliced CFQ IO scheduler, to indicate when a process held FS exclusive resources and thus needed a boost. It doesn't cover all file systems, and it was never fully complete. Lets kill it. Signed-off-by: Justin TerAvest <teravest@google.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq: Remove special treatment for metadata rqs.Justin TerAvest2011-07-101-18/+0
| | | | | | | | | | There is no consistency among filesystems from what bios (or requests) are marked as being metadata. It's interesting to expose this in traces, but we shouldn't schedule the requests differently based on whether or not they're marked as being metadata. Signed-off-by: Justin TerAvest <teravest@google.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* Merge branch 'for-linus' into for-3.1/coreJens Axboe2011-07-011-9/+10
|\ | | | | | | | | | | | | | | Conflicts: block/blk-throttle.c block/cfq-iosched.c Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * cfq-iosched: make code consistentShaohua Li2011-06-271-1/+2
| | | | | | | | | | | | | | | | | | ioc->ioc_data is rcu protectd, so uses correct API to access it. This doesn't change any behavior, but just make code consistent. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Cc: stable@kernel.org # after ab4bd22d Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * cfq-iosched: fix a rcu warningShaohua Li2011-06-271-1/+4
| | | | | | | | | | | | | | | | | | I got a rcu warnning at boot. the ioc->ioc_data is rcu_deferenced, but doesn't hold rcu_read_lock. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Cc: stable@kernel.org # after ab4bd22d Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * block: Add __attribute__((format(printf...) and fix falloutJoe Perches2011-06-131-5/+6
| | | | | | | | | | | | | | | | | | Use the compiler to verify format strings and arguments. Fix fallout. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * cfq-iosched: fix locking around ioc->ioc_data assignmentJens Axboe2011-06-061-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since we are modifying this RCU pointer, we need to hold the lock protecting it around it. This fixes a potential reuse and double free of a cfq io_context structure. The bug has been in CFQ for a long time, it hit very few people but those it did hit seemed to see it a lot. Tracked in RH bugzilla here: https://bugzilla.redhat.com/show_bug.cgi?id=577968 Credit goes to Paul Bolle for figuring out that the issue was around the one-hit ioc->ioc_data cache. Thanks to his hard work the issue is now fixed. Cc: stable@kernel.org Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * cfq-iosched: Remove bogus check in queue_fail pathPaul Bolle2011-06-021-3/+0
| | | | | | | | | | | | | | | | queue_fail can only be reached if cic is NULL, so its check for cic must be bogus. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * CFQ: Fix typo and remove unnecessary semicolonKyungmin Park2011-05-311-4/+4
| | | | | | | | | | | | | | Fix comment typo and remove unnecessary semicolon at macro Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* | block: Add __attribute__((format(printf...) and fix falloutJoe Perches2011-06-131-5/+6
| | | | | | | | | | | | | | | | | | Use the compiler to verify format strings and arguments. Fix fallout. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* | CFQ: make two functions staticPaul Bolle2011-06-061-3/+3
| | | | | | | | | | | | | | Correctly suggested by sparse. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* | cfq-iosched: fix locking around ioc->ioc_data assignmentJens Axboe2011-06-061-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since we are modifying this RCU pointer, we need to hold the lock protecting it around it. This fixes a potential reuse and double free of a cfq io_context structure. The bug has been in CFQ for a long time, it hit very few people but those it did hit seemed to see it a lot. Tracked in RH bugzilla here: https://bugzilla.redhat.com/show_bug.cgi?id=577968 Credit goes to Paul Bolle for figuring out that the issue was around the one-hit ioc->ioc_data cache. Thanks to his hard work the issue is now fixed. Cc: stable@kernel.org Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* | iosched: prevent aliased requests from starving other I/OJeff Moyer2011-06-021-7/+2
|/ | | | | | | | | | | | | | | | | | | | | | | | | | Hi, Jens, If you recall, I posted an RFC patch for this back in July of last year: http://lkml.org/lkml/2010/7/13/279 The basic problem is that a process can issue a never-ending stream of async direct I/Os to the same sector on a device, thus starving out other I/O in the system (due to the way the alias handling works in both cfq and deadline). The solution I proposed back then was to start dispatching from the fifo after a certain number of aliases had been dispatched. Vivek asked why we had to treat aliases differently at all, and I never had a good answer. So, I put together a simple patch which allows aliases to be added to the rb tree (it adds them to the right, though that doesn't matter as the order isn't guaranteed anyway). I think this is the preferred solution, as it doesn't break up time slices in CFQ or batches in deadline. I've tested it, and it does solve the starvation issue. Let me know what you think. Cheers, Jeff Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq-iosched: free cic_index if cfqd allocation failsNamhyung Kim2011-05-241-1/+5
| | | | | | | When struct cfq_data allocation fails, cic_index need to be freed. Signed-off-by: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq-iosched: remove unused 'group_changed' in cfq_service_tree_add()Namhyung Kim2011-05-241-2/+1
| | | | | | | | | | | | The 'group_changed' variable is initialized to 0 and never changed, so checking the variable is meaningless. It is a leftover from 0bbfeb832042 ("cfq-iosched: Always provide group iosolation."). Let's get rid of it. Signed-off-by: Namhyung Kim <namhyung@gmail.com> Cc: Justin TerAvest <teravest@google.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq-iosched: reduce bit operations in cfq_choose_req()Namhyung Kim2011-05-241-9/+5
| | | | | | | | Reduce the number of bit operations in cfq_choose_req() on average (and worst) cases. Signed-off-by: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq-iosched: algebraic simplification in cfq_prio_to_maxrq()Namhyung Kim2011-05-241-1/+1
| | | | | | | | | Simplify the calculation in cfq_prio_to_maxrq(), plus replace CFQ_PRIO_LISTS to IOPRIO_BE_NR since they are the same and IOPRIO_BE_NR looks more reasonable in this context IMHO. Signed-off-by: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq-iosched: Fix a memory leak of per cpu stats for root groupVivek Goyal2011-05-231-0/+5
| | | | | | | | We allocated per cpu stats struct for root group but did not free it. Fix it. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* blk-throttle: Make dispatch stats per cpuVivek Goyal2011-05-201-1/+17
| | | | | | | | | | | | | | | Currently we take blkg_stat lock for even updating the stats. So even if a group has no throttling rules (common case for root group), we end up taking blkg_lock, for updating the stats. Make dispatch stats per cpu so that these can be updated without taking blkg lock. If cpu goes offline, these stats simply disappear. No protection has been provided for that yet. Do we really need anything for that? Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* blk-cgroup: Allow sleeping while dynamically allocating a groupVivek Goyal2011-05-201-33/+95
| | | | | | | | | | | | | | | | Currently, all the cfq_group or throtl_group allocations happen while we are holding ->queue_lock and sleeping is not allowed. Soon, we will move to per cpu stats and also need to allocate the per group stats. As one can not call alloc_percpu() from atomic context as it can sleep, we need to drop ->queue_lock, allocate the group, retake the lock and continue processing. In throttling code, I check the queue DEAD flag again to make sure that driver did not call blk_cleanup_queue() in the mean time. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq-iosched: Fix a possible race with cfq cgroup removal codeVivek Goyal2011-05-201-12/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | blkg->key = cfqd is an rcu protected pointer and hence we used to do call_rcu(cfqd->rcu_head) to free up cfqd after one rcu grace period. The problem here is that even though cfqd is around, there are no gurantees that associated request queue (td->queue) or q->queue_lock is still around. A driver might have called blk_cleanup_queue() and release the lock. It might happen that after freeing up the lock we call blkg->key->queue->queue_ock and crash. This is possible in following path. blkiocg_destroy() blkio_unlink_group_fn() cfq_unlink_blkio_group() Hence, wait for an rcu peirod if there are groups which have not been unlinked from blkcg->blkg_list. That way, if there are any groups which are taking cfq_unlink_blkio_group() path, can safely take queue lock. This is how we have taken care of race in throttling logic also. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq-iosched: Get rid of redundant function parameter "create"Vivek Goyal2011-05-201-9/+9
| | | | | | | | Nobody seems to be using cfq_find_alloc_cfqg() function parameter "create". Get rid of that. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* blk-throttle: Use task_subsys_state() to determine a task's blkio_cgroupVivek Goyal2011-05-161-6/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currentlly we first map the task to cgroup and then cgroup to blkio_cgroup. There is a more direct way to get to blkio_cgroup from task using task_subsys_state(). Use that. The real reason for the fix is that it also avoids a race in generic cgroup code. During remount/umount rebind_subsystems() is called and it can do following with and rcu protection. cgrp->subsys[i] = NULL; That means if somebody got hold of cgroup under rcu and then it tried to do cgroup->subsys[] to get to blkio_cgroup, it would get NULL which is wrong. I was running into this race condition with ltp running on a upstream derived kernel and that lead to crash. So ideally we should also fix cgroup generic code to wait for rcu grace period before setting pointer to NULL. Li Zefan is not very keen on introducing synchronize_wait() as he thinks it will slow down moun/remount/umount operations. So for the time being atleast fix the kernel crash by taking a more direct route to blkio_cgroup. One tester had reported a crash while running LTP on a derived kernel and with this fix crash is no more seen while the test has been running for over 6 days. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq-iosched: read_lock() does not always imply rcu_read_lock()Jens Axboe2011-04-191-14/+6
| | | | | | | | | | | | | For some configurations of CONFIG_PREEMPT that is not true. So get rid of __call_for_each_cic() and always uses the explicitly rcu_read_lock() protected call_for_each_cic() instead. This fixes a potential bug related to IO scheduler removal or online switching. Thanks to Paul McKenney for clarifying this. Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* block: add blk_run_queue_asyncChristoph Hellwig2011-04-181-3/+3
| | | | | | | | | | Instead of overloading __blk_run_queue to force an offload to kblockd add a new blk_run_queue_async helper to do it explicitly. I've kept the blk_queue_stopped check for now, but I suspect it's not needed as the check we do when the workqueue items runs should be enough. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* Fix common misspellingsLucas De Marchi2011-03-311-1/+1
| | | | | | Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
* cfq-iosched: removing unnecessary think time checkingLi, Shaohua2011-03-231-9/+4
| | | | | | | | | | Removing think time checking. A high thinktime queue might means the queue dispatches several requests and then do away. Limitting such queue seems meaningless. And also this can simplify code. This is suggested by Vivek. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq-iosched: Don't clear queue stats when preempt.Justin TerAvest2011-03-231-22/+17
| | | | | | | | | | | | | | | | For v2, I added back lines to cfq_preempt_queue() that were removed during updates for accounting unaccounted_time. Thanks for pointing out that I'd missed these, Vivek. Previous commit "cfq-iosched: Don't set active queue in preempt" wrongly cleared stats for preempting queues when it shouldn't have, because when we choose a queue to preempt, it still isn't necessarily scheduled next. Thanks to Vivek Goyal for figuring this out and understanding how the preemption code works. Signed-off-by: Justin TerAvest <teravest@google.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq-iosched: Don't set active queue in preemptJustin TerAvest2011-03-221-16/+23
| | | | | | | | | | | | | Commit "Add unaccounted time to timeslice_used" changed the behavior of cfq_preempt_queue to set cfqq active. Vivek pointed out that other preemption rules might get involved, so we shouldn't manually set which queue is active. This cleans up the code to just clear the queue stats at preemption time. Signed-off-by: Justin TerAvest <teravest@google.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* cfq-iosched: Don't update group weights when on service treeJustin TerAvest2011-03-171-12/+41
| | | | | | | | | | | | | | | | | | | Version 3 is updated to apply to for-2.6.39/core. For version 2, I took Vivek's advice and made sure we update the group weight from cfq_group_service_tree_add(). If a weight was updated while a group is on the service tree, the calculation for the total weight of the service tree can be adjusted improperly, which either leads to bad service tree weights, or potentially crashes (if total_weight becomes 0). This patch defers updates to the weight until a group is off the service tree. Signed-off-by: Justin TerAvest <teravest@google.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* blk-cgroup: Add unaccounted time to timeslice_used.Justin TerAvest2011-03-121-8/+13
| | | | | | | | | | | | There are two kind of times that tasks are not charged for: the first seek and the extra time slice used over the allocated timeslice. Both of these exported as a new unaccounted_time stat. I think it would be good to have this reported in 'time' as well, but that is probably a separate discussion. Signed-off-by: Justin TerAvest <teravest@google.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* Merge branch 'for-2.6.39/stack-plug' into for-2.6.39/coreJens Axboe2011-03-101-8/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | Conflicts: block/blk-core.c block/blk-flush.c drivers/md/raid1.c drivers/md/raid10.c drivers/md/raid5.c fs/nilfs2/btnode.c fs/nilfs2/mdt.c Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * block: remove per-queue pluggingJens Axboe2011-03-101-8/+0
| | | | | | | | | | | | | | | | Code has been converted over to the new explicit on-stack plugging, and delay users have been converted to use the new API for that. So lets kill off the old plugging along with aops->sync_page(). Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* | Merge branch 'block-for-2.6.39-core' of ↵Jens Axboe2011-03-071-3/+3
|\ \ | | | | | | | | | ssh://master.kernel.org/pub/scm/linux/kernel/git/tj/misc into for-2.6.39/core
| * \ Merge branch 'for-linus' of ../linux-2.6-block into block-for-2.6.39/coreTejun Heo2011-03-041-3/+3
| |\ \ | | |/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This merge creates two set of conflicts. One is simple context conflicts caused by removal of throtl_scheduled_delayed_work() in for-linus and removal of throtl_shutdown_timer_wq() in for-2.6.39/core. The other is caused by commit 255bb490c8 (block: blk-flush shouldn't call directly into q->request_fn() __blk_run_queue()) in for-linus crashing with FLUSH reimplementation in for-2.6.39/core. The conflict isn't trivial but the resolution is straight-forward. * __blk_run_queue() calls in flush_end_io() and flush_data_end_io() should be called with @force_kblockd set to %true. * elv_insert() in blk_kick_flush() should use %ELEVATOR_INSERT_REQUEUE. Both changes are to avoid invoking ->request_fn() directly from request completion path and closely match the changes in the commit 255bb490c8. Signed-off-by: Tejun Heo <tj@kernel.org>
| | * block: add @force_kblockd to __blk_run_queue()Tejun Heo2011-03-021-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __blk_run_queue() automatically either calls q->request_fn() directly or schedules kblockd depending on whether the function is recursed. blk-flush implementation needs to be able to explicitly choose kblockd. Add @force_kblockd. All the current users are converted to specify %false for the parameter and this patch doesn't introduce any behavior change. stable: This is prerequisite for fixing ide oops caused by the new blk-flush implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jan Beulich <JBeulich@novell.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: stable@kernel.org Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* | | cfq-iosched: Fix update_vdisktime logicGui Jianfeng2011-03-071-4/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The update_vdisktime logic is broken since commit b54ce60eb7f61f8e314b8b241b0469eda3bb1d42, st->min_vdisktime never makes a progress. Fix it. Thanks Vivek for pointing it out. Signed-off-by: Gui Jianfeng <guijianfen@cn.fujitsu.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* | | cfq-iosched: give busy sync queue no dispatch limitShaohua Li2011-03-071-2/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If there are a sync and an async queue and the sync queue's think time is small, we can ignore the sync queue's dispatch quantum. Because the sync queue will always preempt the async queue, we don't need to care about async's latency. This can fix a performance regression of aiostress test, which is introduced by commit f8ae6e3eb825. The issue should exist even without the commit, but the commit amplifies the impact. The initial post does the same optimization for RT queue too, but since I have no real workload for it, Vivek suggests to drop it. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* | | cfq-iosched: fix race in cfq_set_request()Jens Axboe2011-03-071-2/+1
|/ / | | | | | | | | | | | | We need to hold the queue lock over the reference increment, it's not atomic anymore. Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* | cfq-iosched: Always provide group isolation.Justin TerAvest2011-03-011-36/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Effectively, make group_isolation=1 the default and remove the tunable. The setting group_isolation=0 was because by default we idle on sync-noidle tree and on fast devices, this can be very harmful for throughput. However, this problem can also be addressed by tuning slice_idle and possibly group_idle on faster storage devices. This change simplifies the CFQ code by removing the feature entirely. Signed-off-by: Justin TerAvest <teravest@google.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* | Merge commit 'v2.6.38-rc6' into for-2.6.39/coreJens Axboe2011-03-011-56/+84
|\| | | | | | | | | | | | | Conflicts: block/cfq-iosched.c Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * cfq-iosched: Don't wait if queue already has requests.Justin TerAvest2011-02-091-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 7667aa0630407bc07dc38dcc79d29cc0a65553c1 added logic to wait for the last queue of the group to become busy (have at least one request), so that the group does not lose out for not being continuously backlogged. The commit did not check for the condition that the last queue already has some requests. As a result, if the queue already has requests, wait_busy is set. Later on, cfq_select_queue() checks the flag, and decides that since the queue has a request now and wait_busy is set, the queue is expired. This results in early expiration of the queue. This patch fixes the problem by adding a check to see if queue already has requests. If it does, wait_busy is not set. As a result, time slices do not expire early. The queues with more than one request are usually buffered writers. Testing shows improvement in isolation between buffered writers. Cc: stable@kernel.org Signed-off-by: Justin TerAvest <teravest@google.com> Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * cfq: rename a function to give it more appropriate nameVivek Goyal2011-01-191-3/+3
| | | | | | | | | | | | | | | | | | o Rename a function to give it more approprate name. We are calculating cfq queue slice and function name gives the impression as if cfq group slice length is being calculated. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * block cfq: compensate preempted queue even if it has no slice assignedShaohua Li2011-01-141-4/+15
| | | | | | | | | | | | | | | | | | If a queue is preempted before it gets slice assigned, the queue doesn't get compensation, which looks unfair. For such queue, we compensate it for a whole slice. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * block cfq: make queue preempt work for queues from different workloadShaohua Li2011-01-141-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I got this: fio-874 [007] 2157.724514: 8,32 m N cfq874 preempt fio-874 [007] 2157.724519: 8,32 m N cfq830 slice expired t=1 fio-874 [007] 2157.724520: 8,32 m N cfq830 sl_used=1 disp=0 charge=1 iops=0 sect=0 fio-874 [007] 2157.724521: 8,32 m N cfq830 set_active wl_prio:0 wl_type:0 fio-874 [007] 2157.724522: 8,32 m N cfq830 Not idling. st->count:1 cfq830 is an async queue, and preempted by a sync queue cfq874. But since we have cfqg->saved_workload_slice mechanism, the preempt is a nop. Looks currently our preempt is totally broken if the two queues are not from the same workload type. Below patch fixes it. This will might make async queue starvation, but it's what our old code does before cgroup is added. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| * Merge branch 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-blockLinus Torvalds2011-01-131-54/+58
| |\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * '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() ...
| | * block cfq: don't use atomic_t for cfq_groupShaohua Li2011-01-071-11/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | cfq_group->ref is used with queue_lock hold, the only exception is cfq_set_request, which looks like a bug to me, so ref doesn't need to be an atomic and atomic operation is slower. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-01 19:22:31 +0000