Date: Fri, 27 Jul 2012 16:00:05 +0100 From: Attilio Rao <attilio@freebsd.org> To: Andrew Boyer <aboyer@averesystems.com> Cc: Ryan Stone <rstone@sandvine.com>, FreeBSD Stable Mailing List <freebsd-stable@freebsd.org>, John Baldwin <jhb@freebsd.org>, Andriy Gapon <avg@freebsd.org> Subject: Re: IPMI hardware watchdogs Re: dell r420/r320 stable/9 Message-ID: <CAJ-FndCrkbDLgHqvGh8gotyN_sPT6yh8En1bWmYL5nADDrYvkw@mail.gmail.com> In-Reply-To: <4ECC422A-F7A8-4F6C-9E9D-01080927C36D@averesystems.com> References: <1343350238.12294.10.camel@powernoodle.corp.yahoo.com> <23294764-F30B-4732-8C41-3F0ECA5F273C@averesystems.com> <CAJ-FndCsSZmKTif7Mn%2BZSMX1rbkgkjytRRY5viGimATDMm5RXQ@mail.gmail.com> <4ECC422A-F7A8-4F6C-9E9D-01080927C36D@averesystems.com>
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On Fri, Jul 27, 2012 at 3:55 PM, Andrew Boyer <aboyer@averesystems.com> wro= te: > > On Jul 27, 2012, at 10:42 AM, Attilio Rao wrote: > >> On Fri, Jul 27, 2012 at 3:33 PM, Andrew Boyer <aboyer@averesystems.com> = wrote: >>> >>> On Jul 26, 2012, at 8:50 PM, Sean Bruno wrote: >>> >>>> For the time being I had to revert the following from my stable/9 tree= . >>>> Otherwise I would get a kernel panic on shutdown from ipmi(4). >>>> >>>> http://svnweb.freebsd.org/base?view=3Drevision&revision=3D237839 >>>> http://svnweb.freebsd.org/base?view=3Drevision&revision=3D221121 >>>> >>> >>> On a somewhat related note: We noticed recently that you can't pet or d= isable the IPMI hardware watchdog once SCHEDULER_STOPPED() is true. This m= eans it can fire unexpectedly while you're dumping core or rebooting, depen= ding on how long the timeout was on the pet before the panic. The ipmi dri= ver will need to process the command differently if the scheduler is stoppe= d. I haven't had time to look at a fix yet. >> >> I recall I fixed that internally for SV, but the key here is that we >> need to find an unified (or a default policy). >> More specifically, do we want the watchdog also covers the kernel dump >> part (because of possible deadlocks when dumping). If the answer is >> yes, we likely need pat the watchdog from within the dumping cycle >> itself. If the answer is no, then we can just disable it when entering >> the panic path. But anyway, we need to identify a default policy that >> makes sense first. >> >> Attilio >> > > For our use case, we need the system to reset if the dump hangs. This means we might likely go to control by hand the watchdog patting in the panic path and more specifically I guess this reduces to patting the watching from within the dumping cycle (there could be other expensive points we can consider but nothing that pop off my head right now). Maybe Ryan can share with us if SV can contribute the code back about that specific part. Attilio --=20 Peace can only be achieved by understanding - A. Einstein
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