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path: root/include/linux/percpu_ida.h
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2014-01-23percpu_ida: Make percpu_ida_alloc + callers accept task state bitmaskKent Overstreet
This patch changes percpu_ida_alloc() + callers to accept task state bitmask for prepare_to_wait() for code like target/iscsi that needs it for interruptible sleep, that is provided in a subsequent patch. It now expects TASK_UNINTERRUPTIBLE when the caller is able to sleep waiting for a new tag, or TASK_RUNNING when the caller cannot sleep, and is forced to return a negative value when no tags are available. v2 changes: - Include blk-mq + tcm_fc + vhost/scsi + target/iscsi changes - Drop signal_pending_state() call v3 changes: - Only call prepare_to_wait() + finish_wait() when != TASK_RUNNING (PeterZ) Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Kent Overstreet <kmo@daterainc.com> Cc: <stable@vger.kernel.org> #3.12+ Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2013-10-25percpu_ida: add an API to return free tagsShaohua Li
Add an API to return free tags, blk-mq-tag will use it. Note, this just returns a snapshot of free tags number. blk-mq-tag has two usages of it. One is for info output for diagnosis. The other is to quickly check if there are free tags for request dispatch checking. Neither requires very precise. Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Shaohua Li <shli@fusionio.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-10-25percpu_ida: add percpu_ida_for_each_freeShaohua Li
Add a new API to iterate free ids. blk-mq-tag will use it. Note, this doesn't guarantee to iterate all free ids restrictly. Caller should be aware of this. blk-mq uses it to do sanity check for request timedout, so can tolerate the limitation. Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Shaohua Li <shli@fusionio.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-10-25percpu_ida: make percpu_ida percpu size/batch configurableShaohua Li
Make percpu_ida percpu size/batch configurable. The block-mq-tag will use it. After block-mq uses percpu_ida to manage tags, performance is improved. My test is done in a 2 sockets machine, 12 process cross the 2 sockets. So if there is lock contention or ipi, should be stressed heavily. Testing is done for null-blk. hw_queue_depth nopatch iops patch iops 64 ~800k/s ~1470k/s 2048 ~4470k/s ~4340k/s Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Shaohua Li <shli@fusionio.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-09-09idr: Percpu idaKent Overstreet
Percpu frontend for allocating ids. With percpu allocation (that works), it's impossible to guarantee it will always be possible to allocate all nr_tags - typically, some will be stuck on a remote percpu freelist where the current job can't get to them. We do guarantee that it will always be possible to allocate at least (nr_tags / 2) tags - this is done by keeping track of which and how many cpus have tags on their percpu freelists. On allocation failure if enough cpus have tags that there could potentially be (nr_tags / 2) tags stuck on remote percpu freelists, we then pick a remote cpu at random to steal from. Note that there's no cpu hotplug notifier - we don't care, because steal_tags() will eventually get the down cpu's tags. We _could_ satisfy more allocations if we had a notifier - but we'll still meet our guarantees and it's absolutely not a correctness issue, so I don't think it's worth the extra code. From akpm: "It looks OK to me (that's as close as I get to an ack :)) v6 changes: - Add #include <linux/cpumask.h> to include/linux/percpu_ida.h to make alpha/arc builds happy (Fengguang) - Move second (cpu >= nr_cpu_ids) check inside of first check scope in steal_tags() (akpm + nab) v5 changes: - Change percpu_ida->cpus_have_tags to cpumask_t (kmo + akpm) - Add comment for percpu_ida_cpu->lock + ->nr_free (kmo + akpm) - Convert steal_tags() to use cpumask_weight() + cpumask_next() + cpumask_first() + cpumask_clear_cpu() (kmo + akpm) - Add comment for alloc_global_tags() (kmo + akpm) - Convert percpu_ida_alloc() to use cpumask_set_cpu() (kmo + akpm) - Convert percpu_ida_free() to use cpumask_set_cpu() (kmo + akpm) - Drop percpu_ida->cpus_have_tags allocation in percpu_ida_init() (kmo + akpm) - Drop percpu_ida->cpus_have_tags kfree in percpu_ida_destroy() (kmo + akpm) - Add comment for percpu_ida_alloc @ gfp (kmo + akpm) - Move to percpu_ida.c + percpu_ida.h (kmo + akpm + nab) v4 changes: - Fix tags.c reference in percpu_ida_init (akpm) Signed-off-by: Kent Overstreet <kmo@daterainc.com> Cc: Tejun Heo <tj@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Nicholas A. Bellinger" <nab@linux-iscsi.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>