Date: Tue, 21 Jan 2014 15:12:30 -0700 From: Scott Long <scott4long@yahoo.com> To: John Baldwin <jhb@freebsd.org> Cc: src-committers@freebsd.org, Neel Natu <neel@freebsd.org>, svn-src-all@freebsd.org, Rui Paulo <rpaulo@felyko.com>, svn-src-head@freebsd.org, Alexander Kabaev <kabaev@gmail.com> Subject: Re: svn commit: r260898 - head/sys/kern Message-ID: <D04BF613-A78D-43B8-A22B-DA8F72D22430@yahoo.com> In-Reply-To: <201401211126.18930.jhb@freebsd.org> References: <201401200159.s0K1xa5X012123@svn.freebsd.org> <1536225.gsjt6oXMt2@pippin.baldwin.cx> <20140120171844.69e065fb@kan.dyndns.org> <201401211126.18930.jhb@freebsd.org>
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On Jan 21, 2014, at 9:26 AM, John Baldwin <jhb@freebsd.org> wrote: > On Monday, January 20, 2014 5:18:44 pm Alexander Kabaev wrote: >> On Mon, 20 Jan 2014 11:32:29 -0500 >> John Baldwin <jhb@freebsd.org> wrote: >>=20 >>> On Sunday 19 January 2014 18:18:03 Rui Paulo wrote: >>>> On 19 Jan 2014, at 17:59, Neel Natu <neel@FreeBSD.org> wrote: >>>>> Author: neel >>>>> Date: Mon Jan 20 01:59:35 2014 >>>>> New Revision: 260898 >>>>> URL: http://svnweb.freebsd.org/changeset/base/260898 >>>>>=20 >>>>> Log: >>>>> Bump up WITNESS_COUNT from 1024 to 1536 so there are sufficient >>>>> entries for >>>>> WITNESS to actually work. >>>>=20 >>>> This value should be automatically tuned... >>>=20 >>> How do you propose to do so? This is the count of locks initialized >>> before witness' own SYSINIT is executed and the array it sizes is >>> allocated statically at compile time. This used to not be a static >>> array, but an intrusive list embedded in locks themselves, but we >>> decided to shave a pointer off of each lock that was only used for >>> that and to use a statically sized table instead. >>>=20 >>> --=20 >>> John Baldwin >>=20 >> As <CONSTANT1> + <CONSTANT2> * MAXCPU, as evidently most recent >> overflows reported were caused by jacking MAXCPU up from its default >> value?=20 >=20 > If raising MAXCPU changes the number of unique lock names used, then = the > locks are named incorrectly. We don't use the 'pid' in the name for > PROC_LOCK precisely so that WITNESS will treat them all the same so > that if if it learns a lock order for pid 37 it enforces the same lock > order for pid 38. Device locks should follow a similar rule. They > should generally not include the device name (and in some cases they > really shouldn't even have the driver name). Why shouldn=92t they have a driver and device name? Wouldn=92t it help = identify possible deadlocks from driver instances calling into each other? Scott
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