On Sun, Feb 15, 2015 at 03:46:54PM +0800, Huang Ying wrote:
> FYI, we noticed the below changes on
>
> git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git locking/core
> commit 871a6bb4916fef3123b6ff749b0dc82680fb0d2a ("mutex: In
> mutex_spin_on_owner(), return true when owner changes")
>
>
> testbox/testcase/testparams: wsm/will-it-scale/performance-writeseek3
>
> e07e0d4cb0c4bfe8 871a6bb4916fef3123b6ff749b
> ---------------- --------------------------
> %stddev %change %stddev
> \ | \
> 24972759 ± 2% -98.3% 417134 ± 9%
> will-it-scale.time.voluntary_context_switches
> 2223 ± 49% +209.6% 6884 ± 10%
> will-it-scale.time.involuntary_context_switches
> 542 ± 32% +91.3% 1037 ± 0% will-it-scale.time.system_time
> 186 ± 30% +86.3% 347 ± 0%
> will-it-scale.time.percent_of_cpu_this_job_got
> 26.11 ± 5% -22.7% 20.18 ± 2% will-it-scale.time.user_time
> 0.09 ± 1% -18.2% 0.07 ± 1% will-it-scale.scalability
> 783528 ± 0% -1.8% 769550 ± 0% will-it-scale.per_process_ops
> 12.27 ± 10% +492.7% 72.73 ± 1%
> perf-profile.cpu-cycles.mutex_optimistic_spin.__mutex_lock_slowpath.mutex_lock.generic_file_write_iter.new_sync_write
> 3.22 ± 26% +1718.0% 58.50 ± 1%
> perf-profile.cpu-cycles.osq_lock.mutex_optimistic_spin.__mutex_lock_slowpath.mutex_lock.generic_file_write_iter
Do you have the results for more/different performance tests for this
commit?
Jason mentioned seeing +5% on one (fserver).
So if, for multiple tests, we see an avg improvement, we might trade
that for this one regression.
If otoh we see a net negative, we'll have to go do something about this.
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