From owner-svn-src-all@FreeBSD.ORG Thu Aug 22 14:58:07 2013 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 6198531F; Thu, 22 Aug 2013 14:58:07 +0000 (UTC) (envelope-from marck@rinet.ru) Received: from woozle.rinet.ru (woozle.rinet.ru [195.54.192.68]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id DD3162352; Thu, 22 Aug 2013 14:58:06 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by woozle.rinet.ru (8.14.5/8.14.5) with ESMTP id r7MEw0Xe014172; Thu, 22 Aug 2013 18:58:00 +0400 (MSK) (envelope-from marck@rinet.ru) Date: Thu, 22 Aug 2013 18:58:00 +0400 (MSK) From: Dmitry Morozovsky To: "Kenneth D. Merry" Subject: Re: svn commit: r254615 - head/sys/dev/mps In-Reply-To: <20130822142107.GA49996@nargothrond.kdm.org> Message-ID: References: <201308212130.r7LLUvO5008991@svn.freebsd.org> <20130822142107.GA49996@nargothrond.kdm.org> User-Agent: Alpine 2.00 (BSF 1167 2008-08-23) X-NCC-RegID: ru.rinet X-OpenPGP-Key-ID: 6B691B03 MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (woozle.rinet.ru [0.0.0.0]); Thu, 22 Aug 2013 18:58:00 +0400 (MSK) Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Aug 2013 14:58:07 -0000 On Thu, 22 Aug 2013, Kenneth D. Merry wrote: > > > Fix mps(4) driver breakage that came in in change 253550 that > > > manifested itself in out of chain frame conditions. > > > > > > When the driver ran out of chain frames, the request in question > > > would get completed early, and go through mpssas_scsiio_complete(). > > what is real impact of the bug? > > Your system will essentially hang, certainly as far as anything connected > to the controller in question. [snip] > 5. Look for an out of chain frames message on the console. To see how far > you are towards using the chain frames, run 'sysctl dev.mps'. You can see > how many chain frames you have free, and how many requests have failed. > > This change just needs to be merged along with the other changes to avoid > having the regression in stable. Thank you very much for the explanation. We use a couple of servers with mps (and many spindles there), all on stable/9 from this summer, and you commit turns on an alarm light in my head ;) -- Sincerely, D.Marck [DM5020, MCK-RIPE, DM3-RIPN] [ FreeBSD committer: marck@FreeBSD.org ] ------------------------------------------------------------------------ *** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru *** ------------------------------------------------------------------------