From owner-freebsd-current@FreeBSD.ORG Tue May 19 13:35:29 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B02CF106566B for ; Tue, 19 May 2009 13:35:29 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id 80F418FC18 for ; Tue, 19 May 2009 13:35:29 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id 328A746B09; Tue, 19 May 2009 09:35:29 -0400 (EDT) Received: from jhbbsd.hudson-trading.com (unknown [209.249.190.8]) by bigwig.baldwin.cx (Postfix) with ESMTPA id 0FB7F8A028; Tue, 19 May 2009 09:35:28 -0400 (EDT) From: John Baldwin To: Ben Kelly Date: Tue, 19 May 2009 08:31:48 -0400 User-Agent: KMail/1.9.7 References: <08D7DC2A-68BE-47B6-8D5D-5DE6B48F87E5@wanderview.com> <200905181129.51526.jhb@freebsd.org> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200905190831.48523.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.0.1 (bigwig.baldwin.cx); Tue, 19 May 2009 09:35:28 -0400 (EDT) X-Virus-Scanned: clamav-milter 0.95 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-2.5 required=4.2 tests=AWL,BAYES_00,RDNS_NONE autolearn=no version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on bigwig.baldwin.cx Cc: Adam McDougall , freebsd-current@freebsd.org, Artem Belevich Subject: Re: [patch] zfs livelock and thread priorities X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 May 2009 13:35:29 -0000 On Monday 18 May 2009 10:16:46 pm Ben Kelly wrote: > On May 18, 2009, at 11:29 AM, John Baldwin wrote: > > 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. > > If this approach was taken would it make sense to use a flag to > indicate "use the specified priority" since 0 is a valid priority value? Well, 0 isn't truly valid (it's sort of reserved I guess), and we already use 0 for tsleep() to mean "don't change my priority". However, I would almost be inclined to just KASSERT() that the priority argument is not 0 and require each place that creates a kthread to explicitly set the new thread's priority. -- John Baldwin