Date: Thu, 30 Sep 2010 09:11:22 +0300 From: Andriy Gapon <avg@icyb.net.ua> To: Don Lewis <truckman@FreeBSD.org> Cc: stable@FreeBSD.org, sterling@camdensoftware.com, freebsd@jdc.parodius.com Subject: Re: CPU time accounting broken on 8-STABLE machine after a few hours of uptime Message-ID: <4CA42A0A.6090003@icyb.net.ua> In-Reply-To: <201009292327.o8TNRTPa077418@gw.catspoiler.org> References: <201009292327.o8TNRTPa077418@gw.catspoiler.org>
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on 30/09/2010 02:27 Don Lewis said the following: > On 29 Sep, Andriy Gapon wrote: >> on 29/09/2010 11:56 Don Lewis said the following: >>> I'm using the same kernel config as the one on a slower !SMP box which >>> I'm trying to squeeze as much performance out of as possible. My kernel >>> config file contains these statements: >>> nooptions SMP >>> nodevice apic >>> >>> Testing with an SMP kernel is on my TODO list. >> >> SMP or not, it's really weird to see apic disabled nowadays. > > I tried enabling apic and got worse results. I saw ping RTTs as high as > 67 seconds. Here's the timer info with apic enabled: I didn't expect anything to change in this output with APIC enabled. > # sysctl kern.timecounter > kern.timecounter.tick: 1 > kern.timecounter.choice: TSC(800) ACPI-fast(1000) i8254(0) dummy(-1000000) > kern.timecounter.hardware: ACPI-fast > kern.timecounter.stepwarnings: 0 > kern.timecounter.tc.i8254.mask: 65535 > kern.timecounter.tc.i8254.counter: 53633 > kern.timecounter.tc.i8254.frequency: 1193182 > kern.timecounter.tc.i8254.quality: 0 > kern.timecounter.tc.ACPI-fast.mask: 16777215 > kern.timecounter.tc.ACPI-fast.counter: 7988816 > kern.timecounter.tc.ACPI-fast.frequency: 3579545 > kern.timecounter.tc.ACPI-fast.quality: 1000 > kern.timecounter.tc.TSC.mask: 4294967295 > kern.timecounter.tc.TSC.counter: 1341917999 > kern.timecounter.tc.TSC.frequency: 2500014018 > kern.timecounter.tc.TSC.quality: 800 > kern.timecounter.invariant_tsc: 0 > > Here's the verbose boot info with apic: > <http://people.freebsd.org/~truckman/AN-M2_HD-8.1-STABLE-apic-verbose.txt>; vmstat -i ? > I've also experimented with SMP as well as SCHED_4BSD (all previous > testing was with !SMP and SCHED_ULE). I still see occasional problems > with SCHED_4BSD and !SMP, but so far I have not seen any problems with > SCHED_ULE and SMP. Good! > I did manage to catch the problem with lock profiling enabled: > <http://people.freebsd.org/~truckman/AN-M2_HD-8.1-STABLE_lock_profile_freeze.txt>; > I'm currently testing SMP some more to verify if it really avoids this > problem. OK. -- Andriy Gapon
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