Date: Mon, 18 May 2009 19:12:59 +0200 From: Attilio Rao <attilio@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: Adam McDougall <mcdouga9@egr.msu.edu>, freebsd-current@freebsd.org, Artem Belevich <fbsdlist@src.cx>, Ben Kelly <ben@wanderview.com> Subject: Re: [patch] zfs livelock and thread priorities Message-ID: <3bbf2fe10905181012t4bde260bp31181e3ea7b03a42@mail.gmail.com> In-Reply-To: <200905181129.51526.jhb@freebsd.org> References: <08D7DC2A-68BE-47B6-8D5D-5DE6B48F87E5@wanderview.com> <20090516031332.GG82547@egr.msu.edu> <5D988481-068A-4AB3-952E-255BEA1D9DA7@wanderview.com> <200905181129.51526.jhb@freebsd.org>
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2009/5/18 John Baldwin <jhb@freebsd.org>: > On Saturday 16 May 2009 12:40:44 pm Ben Kelly wrote: >> 1) It changes the kproc(9) API by adding a kproc_create_priority() >> function that allows you to set the priority of the newly created >> thread. I'm not sure how people feel about this. > > Actually, I almost think we should just add a priority argument to each of the > routines that creates a new kthread/kproc. Perhaps allow a priority of 0 to > let the thread run with the default priority. Hmm, it looks like kthreads > default to running with whatever thread0 runs at (PVM) which is probably not > really ideal. Having an explicit priority for every kthread would probably > be best. Most kthreads should probably be at PZERO by default I think. I'm not sure I agree here. 1) Maybe I missed it (so please point me to the right one) but I didn't see a deep analysis of what messed up with the priorities there 2) I think this KPI can be dangerous and lead to problems. Priority is something highly fragile. Thanks, Attilio -- Peace can only be achieved by understanding - A. Einsteinhelp
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