On Wed, 2013-06-19 at 21:58 +0200, Oleg Nesterov wrote:
> On 06/19, David Ahern wrote:
> >
> > On 6/19/13 11:51 AM, Oleg Nesterov wrote:
> >>
> >> not sure these numbers actually mean
> >> something, but still.
>
> Yes.
>
> >> So, the test-case:
> >>
> >> int pipe1[2], pipe2[2];
> >
> > Same as "perf bench sched pipe"
>
> You just cruelly disclosed the fact that I do not use perf.
>
> Thanks. So,
>
> # perf record -e sched:sched_switch -p1 &
> [1] 516
> # perf bench sched pipe
>
> 3 times.
>
> before:
>
> Total time: 30.119 [sec]
>
> 30.119501 usecs/op
> 33201 ops/sec
>
> Total time: 30.634 [sec]
>
> 30.634105 usecs/op
> 32643 ops/sec
>
> Total time: 30.100 [sec]
>
> 30.100209 usecs/op
> 33222 ops/sec
>
>
> after:
>
> Total time: 29.645 [sec]
>
> 29.645941 usecs/op
> 33731 ops/sec
>
> Total time: 29.759 [sec]
>
> 29.759075 usecs/op
> 33603 ops/sec
>
> Total time: 29.803 [sec]
>
> 29.803522 usecs/op
> 33553 ops/sec
>
> Hmm. Actually sched-pipe.c is a bit more "heavy", it does switch_mm().
> And I used taskset. But it seems that this test-case shows the similar
> results.
>
OK, I tested this against 3.10-rc6 and then applied your patches (had to
modify a little because it didn't apply that cleanly).
I ran this:
perf stat --repeat 100 -- perf bench sched pipe >
/tmp/perf-bench-sched.{before, after}
before:
# tail -20 perf-bench-sched.before
24.115329 usecs/op
41467 ops/sec
Performance counter stats for 'perf bench sched pipe' (100 runs):
17851.057092 task-clock # 0.741 CPUs utilized
( +- 0.03% )
1,996,681 context-switches # 0.112 M/sec
( +- 0.00% )
61 cpu-migrations # 0.003 K/sec
( +- 2.13% )
1,248 page-faults # 0.070 K/sec
( +- 0.01% )
29,738,460,230 cycles # 1.666 GHz
( +- 0.03% ) [50.91%]
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
22,108,278,276 instructions # 0.74 insns per cycle
( +- 0.01% ) [76.35%]
5,275,965,301 branches # 295.555 M/sec
( +- 0.00% ) [74.14%]
69,232,340 branch-misses # 1.31% of all branches
( +- 0.19% ) [74.95%]
24.089150300 seconds time elapsed
( +- 0.02% )
after:
# tail -20 perf-bench-sched.after
24.170945 usecs/op
41371 ops/sec
Performance counter stats for 'perf bench sched pipe' (100 runs):
18060.703178 task-clock # 0.747 CPUs utilized
( +- 0.02% )
1,996,865 context-switches # 0.111 M/sec
( +- 0.00% )
63 cpu-migrations # 0.003 K/sec
( +- 3.07% )
1,248 page-faults # 0.069 K/sec
( +- 0.01% )
29,596,801,452 cycles # 1.639 GHz
( +- 0.02% ) [49.13%]
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
22,033,684,587 instructions # 0.74 insns per cycle
( +- 0.01% ) [73.34%]
5,281,256,193 branches # 292.417 M/sec
( +- 0.00% ) [75.84%]
66,966,995 branch-misses # 1.27% of all branches
( +- 0.22% ) [75.04%]
24.183738898 seconds time elapsed
( +- 0.01% )
Maybe I did something wrong, but on this box, I didn't see any
significant improvement with the patches. Note, I did the test before
applying all patches, and then again after applying all patches.
-- Steve
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