Date: Wed, 25 Jan 2012 23:14:53 +0100 From: Florian Smeets <flo@FreeBSD.org> To: Andriy Gapon <avg@FreeBSD.org> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r228424 - in head/sys: kern sys Message-ID: <4F207EDD.1000407@FreeBSD.org> In-Reply-To: <4F207B55.4020500@FreeBSD.org> References: <201112112102.pBBL21kB068967@svn.freebsd.org> <4F1DE4FF.3080606@FreeBSD.org> <4F207B55.4020500@FreeBSD.org>
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[-- Attachment #1 --] On 25.01.12 22:59, Andriy Gapon wrote: > 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. > [mangled ministat removed] > >> 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. > [mangled ministat removed] > > > Is it possible to see ministat's report for the difference between > 228424-40-sf10 and 228424-40-sf10-cl datasets? > Sure, here we go. x 228424-40-sf10 + 228424-40-sf10-cl +----------------------------------------------------------------------+ |x + + + x ++x + x + + ++ x x x| | |____________________M_A_____________________| | | |______________A__M__________| | +----------------------------------------------------------------------+ N Min Max Median Avg Stddev x 10 194093.35 198864.83 196129.36 196214.69 1545.8783 + 10 194288.28 197083.85 195955.26 195733.15 1012.3529 No difference proven at 95.0% confidence >> 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 :-) > Florian [1] http://people.freebsd.org/~attilio/cachelineunshare.patch [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- iEYEARECAAYFAk8gft4ACgkQapo8P8lCvwnSvACghSPbOTJMy4j/4pCGtP/+ZXn8 oOkAn3GQd9LA3SznCIMd1IE57PuQvwtv =hrC0 -----END PGP SIGNATURE-----
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