* [rcu] 10a94227ba2: -2.0% will-it-scale.per_process_ops
@ 2014-04-19 8:26 Fengguang Wu
2014-04-22 1:56 ` Paul E. McKenney
0 siblings, 1 reply; 2+ messages in thread
From: Fengguang Wu @ 2014-04-19 8:26 UTC (permalink / raw)
To: Paul E. McKenney; +Cc: LKML, lkp
Paul,
FYI, we noticed the below changes on
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git next.2014.04.16b
commit 10a94227ba229f1b05672754dc318a8fe7982c95 ("rcu: Update cpu_needs_another_gp() for futures from non-NOCB CPUs")
test case: nhm4/micro/will-it-scale/lseek1
11ba5ab363b9359 10a94227ba229f1b05672754d
--------------- -------------------------
11210675 ~ 0% -2.0% 10985451 ~ 0% TOTAL will-it-scale.per_process_ops
1.24 ~ 5% -33.4% 0.83 ~ 5% TOTAL perf-profile.cpu-cycles.trace_hardirqs_off_caller.lseek64
3.88 ~ 2% +49.0% 5.79 ~ 0% TOTAL perf-profile.cpu-cycles.trace_hardirqs_on_thunk.lseek64
295 ~16% +27.0% 375 ~ 8% TOTAL cpuidle.C1E-NHM.usage
45061 ~ 2% +16.7% 52590 ~ 2% TOTAL cpuidle.C6-NHM.usage
1.21 ~ 4% +5.8% 1.28 ~ 4% TOTAL perf-profile.cpu-cycles.shmem_file_llseek.sys_lseek.system_call_fastpath.lseek64
4206 ~ 1% -78.6% 900 ~ 8% TOTAL interrupts.IWI
14303 ~ 1% +26.7% 18120 ~ 1% TOTAL interrupts.0:IO-APIC-edge.timer
3228 ~ 4% -17.2% 2672 ~ 6% TOTAL interrupts.RES
182 ~ 2% -8.1% 167 ~ 3% TOTAL time.user_time
235 ~ 2% +6.2% 250 ~ 2% TOTAL time.system_time
379471 ~ 0% +1.2% 384127 ~ 0% TOTAL interrupts.LOC
Legend:
~XX% - stddev percent
[+-]XX% - change percent
It does effectively eliminate interrupts.IWI:
interrupts.IWI
4500 ++-*-----*-------*--------------------------------------------------+
|.. *. + .*. .*..*. .*..*..*.. .*..*..*..*.*..*..*
4000 *+ *. *. *. *.. .*..*. |
3500 ++ * |
| |
3000 ++ |
2500 ++ |
| |
2000 ++ |
1500 ++ |
| |
1000 ++ O O O O O O O
500 ++ O |
| |
0 O+-O--O--O-O--O--O--O--O--O-O--O--O--O--O--O-O----------------------+
[*] bisect-good sample
[O] bisect-bad sample
Thanks,
Fengguang
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [rcu] 10a94227ba2: -2.0% will-it-scale.per_process_ops
2014-04-19 8:26 [rcu] 10a94227ba2: -2.0% will-it-scale.per_process_ops Fengguang Wu
@ 2014-04-22 1:56 ` Paul E. McKenney
0 siblings, 0 replies; 2+ messages in thread
From: Paul E. McKenney @ 2014-04-22 1:56 UTC (permalink / raw)
To: Fengguang Wu; +Cc: LKML, lkp
On Sat, Apr 19, 2014 at 04:26:22PM +0800, Fengguang Wu wrote:
> Paul,
>
> FYI, we noticed the below changes on
>
> git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git next.2014.04.16b
> commit 10a94227ba229f1b05672754dc318a8fe7982c95 ("rcu: Update cpu_needs_another_gp() for futures from non-NOCB CPUs")
>
> test case: nhm4/micro/will-it-scale/lseek1
>
> 11ba5ab363b9359 10a94227ba229f1b05672754d
> --------------- -------------------------
> 11210675 ~ 0% -2.0% 10985451 ~ 0% TOTAL will-it-scale.per_process_ops
> 1.24 ~ 5% -33.4% 0.83 ~ 5% TOTAL perf-profile.cpu-cycles.trace_hardirqs_off_caller.lseek64
> 3.88 ~ 2% +49.0% 5.79 ~ 0% TOTAL perf-profile.cpu-cycles.trace_hardirqs_on_thunk.lseek64
> 295 ~16% +27.0% 375 ~ 8% TOTAL cpuidle.C1E-NHM.usage
> 45061 ~ 2% +16.7% 52590 ~ 2% TOTAL cpuidle.C6-NHM.usage
> 1.21 ~ 4% +5.8% 1.28 ~ 4% TOTAL perf-profile.cpu-cycles.shmem_file_llseek.sys_lseek.system_call_fastpath.lseek64
> 4206 ~ 1% -78.6% 900 ~ 8% TOTAL interrupts.IWI
> 14303 ~ 1% +26.7% 18120 ~ 1% TOTAL interrupts.0:IO-APIC-edge.timer
> 3228 ~ 4% -17.2% 2672 ~ 6% TOTAL interrupts.RES
> 182 ~ 2% -8.1% 167 ~ 3% TOTAL time.user_time
> 235 ~ 2% +6.2% 250 ~ 2% TOTAL time.system_time
> 379471 ~ 0% +1.2% 384127 ~ 0% TOTAL interrupts.LOC
>
> Legend:
> ~XX% - stddev percent
> [+-]XX% - change percent
>
> It does effectively eliminate interrupts.IWI:
>
> interrupts.IWI
>
> 4500 ++-*-----*-------*--------------------------------------------------+
> |.. *. + .*. .*..*. .*..*..*.. .*..*..*..*.*..*..*
> 4000 *+ *. *. *. *.. .*..*. |
> 3500 ++ * |
> | |
> 3000 ++ |
> 2500 ++ |
> | |
> 2000 ++ |
> 1500 ++ |
> | |
> 1000 ++ O O O O O O O
> 500 ++ O |
> | |
> 0 O+-O--O--O-O--O--O--O--O--O-O--O--O--O--O--O-O----------------------+
>
>
> [*] bisect-good sample
> [O] bisect-bad sample
OK, so we get rid of interrupts.IWI (not sure what those are), and
we also seem to increase the idle time (cpuidle.C1E-NHM.usage and
cpuidle.C6-NHM.usage), which also seem like good things. The overall
benchmark number looks to get a bit worse, though. Not sure why lseek()
would incur more hardirqs, but also unsure what the units are (3.88 of
what exactly?). Not sure why there would be more timer interrutpts,
unless my interpretation of the cpuidle stats is backwards, in which
case it would be a natural consequence of there being less idle time.
Any of this speculation at all relevant? ;-)
Thanx, Paul
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