Date: Fri, 27 Feb 2009 09:44:21 -0600 From: Guy Helmer <ghelmer@palisadesys.com> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-stable@freebsd.org Subject: Re: 7.1 hangs in cache_lookup mutex? Message-ID: <49A80A55.5070004@palisadesys.com> In-Reply-To: <200902261753.29607.jhb@freebsd.org> References: <49A46AB4.3080003@palisadesys.com> <200902261648.32845.jhb@freebsd.org> <49A7173B.4030608@palisadesys.com> <200902261753.29607.jhb@freebsd.org>
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John Baldwin wrote: > On Thursday 26 February 2009 5:27:07 pm Guy Helmer wrote: > >> John Baldwin wrote: >> >>> On Thursday 26 February 2009 4:22:15 pm Guy Helmer wrote: >>> >>> >>>> db> show sleepchain 23110 >>>> thread 100181 (pid 23110, vmstat) blocked on sx "user map" XLOCK >>>> thread 100208 (pid 23092, kvoop) is on a run queue >>>> db> show sleepchain 23092 >>>> thread 100208 (pid 23092, kvoop) is on a run queue >>>> >>>> >>> Ah, so this is normal (well, mostly) in that kvoop is simply on the run >>> > queue > >>> waiting for a CPU. Can you find the thread pointer for kvoop and check on >>> things such as if it is pinned and if so to which CPU (td_pinned will tell >>> you the first, and td_sched->ts_cpu will tell you the second with ULE). >>> >>> >> (kgdb) print td->td_pinned >> $2 = 0 >> > > Ok, not pinned. > > >> From my captured ddb run: >> cpuid = 3 >> curthread = 0xc5e2f000: pid 23090 "filter" >> curpcb = 0xe6f90d90 >> fpcurthread = none >> idlethread = 0xc442daf0: pid 11 "idle: cpu3" >> APIC ID = 7 >> currentldt = 0x50 >> spin locks held: >> > > At http://www.freebsd.org/~jhb/gdb/ you can find my kgdb scripts. If you > source gdb6 you can run 'runtds' which will show you what each CPU is doing > (more or less) in ps-style output. > > >> I sure wish I could find the root cause of the hangs. On a hunch, I >> tried setting "machdep.cpu_idle_hlt=0" on the amd64 machine, and it has >> run 32 hours without a hang. It could just be coincidence, though... >> > > Ahhh, that actually could explain it perhaps. Do your CPUs support C2 or > higher sleep states for idle? You can try limiting it to only C1 (or disable > C1E in your BIOS if it has an option for that) to see if that fixes it. > > I don't think the CPUs support anything lower than C1 - there is no hw.acpi.cpu.cx_supported sysctl node, and hw.cpi.cpu.cx_lowest is C1. C1-Enhanced was already disabled in the BIOS, at least on the machine running amd64. 48 hours of runtime, and no hangs seen yet. I did reboot it this morning to check the sleep settings in the BIOS. Guy
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