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| author | Tejun Heo <tj@kernel.org> | 2012-02-07 07:51:30 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2012-02-07 07:51:30 +0100 |
| commit | 11a3122f6cf2d988a77eb8883d0fc49cd013a6d5 (patch) | |
| tree | ded8ea8a2982754ff0c58448a7ed2e59487104cb /kernel/fork.c | |
| parent | 822bfa51ce44f2c63c300fdb76dc99c4d5a5ca9f (diff) | |
| download | lwn-11a3122f6cf2d988a77eb8883d0fc49cd013a6d5.tar.gz lwn-11a3122f6cf2d988a77eb8883d0fc49cd013a6d5.zip | |
block: strip out locking optimization in put_io_context()
put_io_context() performed a complex trylock dancing to avoid
deferring ioc release to workqueue. It was also broken on UP because
trylock was always assumed to succeed which resulted in unbalanced
preemption count.
While there are ways to fix the UP breakage, even the most
pathological microbench (forced ioc allocation and tight fork/exit
loop) fails to show any appreciable performance benefit of the
optimization. Strip it out. If there turns out to be workloads which
are affected by this change, simpler optimization from the discussion
thread can be applied later.
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <1328514611.21268.66.camel@sli10-conroe>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 051f090d40c1..c574aefa8d1b 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -890,7 +890,7 @@ static int copy_io(unsigned long clone_flags, struct task_struct *tsk) return -ENOMEM; new_ioc->ioprio = ioc->ioprio; - put_io_context(new_ioc, NULL); + put_io_context(new_ioc); } #endif return 0; |