On Thu, 2015-01-08 at 10:27 +0800, Huang Ying wrote:
> FYI, we noticed the below changes on
>
> commit c8c06efa8b552608493b7066c234cfa82c47fcea ("mm: convert i_mmap_mutex to
> rwsem")
>
>
> testbox/testcase/testparams: lituya/unixbench/performance-execl
>
> 83cde9e8ba95d180 c8c06efa8b552608493b7066c2
> ---------------- --------------------------
> %stddev %change %stddev
> \ | \
> 721721 ± 1% +303.6% 2913110 ± 3%
> unixbench.time.voluntary_context_switches
> 11767 ± 0% -7.6% 10867 ± 1% unixbench.score
I simply cannot reproduce this, not even on a large box.
mutex (83cde9e8ba95d180):
run1:
Execl Throughput 3974.3 lps (30.0 s, 2 samples)
Voluntary context switches: 377039
run2:
Execl Throughput 4115.5 lps (30.0 s, 2 samples)
Voluntary context switches: 391260
run3:
Execl Throughput 4000.2 lps (30.0 s, 2 samples)
Voluntary context switches: 378674
rwsem (c8c06efa8b552608493b7066c2):
run1:
Execl Throughput 4166.0 lps (30.0 s, 2 samples)
Voluntary context switches: 385740
run2:
Execl Throughput 4115.5 lps (30.0 s, 2 samples)
Voluntary context switches: 391260
run3:
Execl Throughput 4110.5 lps (29.9 s, 2 samples)
Voluntary context switches: 387053
Since throughput is in the ballpark, so is the benchmark score (in fact
the rwsem score is slightly better).
Is this a one time thing or can you observe it again? Any special things
you guys are doing when running the benchmark? Here are some things I've
done: cpu gov set to performance, Unixbench taken from
(http://byte-unixbench.googlecode.com/files/UnixBench5.1.3.tgz ), used
default compiler options from unixbench Makefile (that is using the
solaris 2 option). This pretty much matches the environment info you've
provided. We've done this lock type comparison exercise plenty of times
in the past, and I'm a bit surprised to see your numbers.
Thanks,
Davidlohr
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
