Date: Tue, 26 Aug 2014 22:35:21 +0300 From: Alexander Motin <mav@FreeBSD.org> To: Slawa Olhovchenkov <slw@zxy.spb.ru>, Adrian Chadd <adrian@freebsd.org> Cc: "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org> Subject: Re: svn commit: r265792 - head/sys/kern Message-ID: <53FCE179.9030804@FreeBSD.org> In-Reply-To: <20140826185407.GE2075@zxy.spb.ru> References: <201405100053.s4A0rbF9080571@svn.freebsd.org> <20140511083114.GA53503@zxy.spb.ru> <CAJ-Vmo=x-JkHSVDT4REWQ_g=vb45T%2BTfrpZ8bc28NNbPd-ZYsg@mail.gmail.com> <20140520154113.GA23318@zxy.spb.ru> <CAJ-Vmonby1MVuuJnWoXcPh1cTE1q0SQEQhfL_ESzoDEWHtKcCw@mail.gmail.com> <20140826185407.GE2075@zxy.spb.ru>
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On 26.08.2014 21:54, Slawa Olhovchenkov wrote: > On Tue, May 20, 2014 at 09:04:25AM -0700, Adrian Chadd wrote: > >> On 20 May 2014 08:41, Slawa Olhovchenkov <slw@zxy.spb.ru> wrote: >> >>>> (But if you try it on 10.0 and it changes things, by all means let me know.) >>> >>> I am try on 10.0, but not sure about significant improvement (may be >>> 10%). >>> >>> For current CPU (E5-2650 v2 @ 2.60GHz) hwpmc don't working (1. after >>> collect some data `pmcstat -R sample.out -G out.txt` don't decode any; >>> 2. kldunload hwpmc do kernel crash) and I can't collect detailed >>> profile information. >> >> Yup. I'm starting to get really ticked off at how pmc logging on >> multi-core devices just "stops" after a while. I'll talk with other >> pmc people and see if we can figure out what the heck is going on. :( > > Now I can test you work on CPU w/ working pmc. > @ CPU_CLK_UNHALTED_CORE [241440 samples] > > 10.59% [25561] _mtx_lock_spin_cookie @ /boot/kernel/kernel > 94.25% [24092] pmclog_reserve @ /boot/kernel/hwpmc.ko > 100.0% [24092] pmclog_process_callchain > 100.0% [24092] pmc_process_samples > 100.0% [24092] pmc_hook_handler > 100.0% [24092] hardclock_cnt @ /boot/kernel/kernel Slava, on large SMP systems you should specify some much bigger division rate (like `-n 100000000`) when doing PMC sampling. Otherwise you are mostly measuring PMC's internal lock congestion. -- Alexander Motin
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