svn commit: r228424 - in head/sys: kern sys
Andriy Gapon
avg at FreeBSD.org
Wed Jan 25 21:59:53 UTC 2012
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on 24/01/2012 00:53 Florian Smeets said the following:
> On 11.12.11 22:02, Andriy Gapon wrote:
>> Author: avg Date: Sun Dec 11 21:02:01 2011 New Revision: 228424 URL:
>> http://svn.freebsd.org/changeset/base/228424
>>
>> Log: panic: add a switch and infrastructure for stopping other CPUs in
>> SMP case
>>
>
> Hi,
>
> Attilio asked me to verify that this commit does not introduce a
> performance regression.
First of all, thank you very much for doing this!
> The box used to run these tests was a 40 Core 32GB Xeon box (HTT was turned
> off, so 40 real hardware cores). As benchmark pgbench/PostgreSQL were used,
> a snapshot of PostgreSQL 9.2 from 16.01.2012 was used as they did a lot of
> scaling work in 9.2 which improved the numbers quite a lot vs. 9.1. The
> initial benchmarks were run with a scaling factor of 100 which creates a
> database work set of ~1.5GB. Max throughput was achieved at 20 Clients.
>
> x 228423-20 + 228424-20
> +----------------------------------------------------------------------+ |
> x + | |x x x
> +* + + xxx * ++ + + x| |
> |___________________A______M_____________| | |
> |___________A____M_____| |
> +----------------------------------------------------------------------+ N
> Min Max Median Avg Stddev x 10
> 111073.26 115016.79 113113.49 112745.69 1169.2132 + 10
> 112583.56 114454.33 113668.08 113343.31 661.31761 No
> difference proven at 95.0% confidence
>
> At 40 threads the results varied between 43000 - 76500 across reboots.
> Attilio suspects that this can be caused by the kernel memory layout
> changing under the woods creating cache effects difficult to control,
> therefor the scaling factor was reduced to 10 (~150MB work set) and the
> numbers got deterministic across reboot.
>
> x 228423-40-sf10 + 228424-40-sf10 * 228424-40-sf10-cl
> +----------------------------------------------------------------------+ |x
> x x *** * * + x **+ *+ * * ** + + +| |
> |__________A__________| | |
> |______________MA________________| | |
> |__________A__M_______| |
> +----------------------------------------------------------------------+ N
> Min Max Median Avg Stddev x 10
> 192489.43 196045.39 194138.34 194149.19 986.61561 + 10
> 194093.35 198864.83 196129.36 196214.69 1545.8783
> Difference at 95.0% confidence 2065.5 +/- 1218.43 1.06387% +/- 0.627572%
> (Student's t, pooled s = 1296.76) * 10 194288.28 197083.85
> 195955.26 195733.15 1012.3529 Difference at 95.0% confidence
> 1583.96 +/- 939.189 0.815847% +/- 0.483746% (Student's t, pooled s =
> 999.567)
Is it possible to see ministat's report for the difference between
228424-40-sf10 and 228424-40-sf10-cl datasets?
> The 228424-40-sf10-cl results are with a patch from Attilio [1] which he
> will followup on.
I like the patch already, regardless of how much performance difference it
produces :-)
> If anybody wants to look at the raw numbers they are available at [2].
>
> There are results for pbzip2 runs here [3] also, the numbers are "real"
> time from /usr/bin/time.
>
> Cheers, Florian
>
> [1] http://people.freebsd.org/~attilio/cachelineunshare.patch [2]
> http://tb.smeets.im/~flo/stop-sched/pgsql/ [3]
> http://tb.smeets.im/~flo/stop-sched/pbzip2/
>
- --
Andriy Gapon
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