From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Christie Subject: Re: [Ksummit-2005-discuss] Summary of 2005 Kernel Summit Proposed Topics Date: Wed, 30 Mar 2005 12:10:58 -0800 Message-ID: <424B07D2.4030309@cs.wisc.edu> References: <20050327054831.GA15453@waste.org> <1111905181.4753.15.camel@mylaptop> <20050326224621.61f6d917.davem@davemloft.net> <1112027284.5531.27.camel@mulgrave> <20050329152008.GD63268@muc.de> <1112116762.5088.65.camel@beastie> <1112130512.1077.107.camel@jzny.localdomain> <20050330152208.GB12672@muc.de> <20050330172412.GP15453@waste.org> <1112204383.11620.2.camel@beastie> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: open-iscsi@googlegroups.com, Andi Kleen , jamal , James Bottomley , Rik van Riel , andrea@suse.de, ksummit-2005-discuss@thunk.org, netdev Return-path: To: Dmitry Yusupov In-Reply-To: <1112204383.11620.2.camel@beastie> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Dmitry Yusupov wrote: > On Wed, 2005-03-30 at 09:24 -0800, Matt Mackall wrote: > >>I seem to recall this being fairly easy to trigger by simply pulling >>the network cable while there's heavy mmap + write load. The system >>will quickly spiral down into OOM and will remain wedged when you plug >>the network back in. With iSCSI, after some extended period all the >>I/Os will have SCSI timeouts and lose everything. > > > We've discussed that already. SCSI timeout logic just doesn't fit. (see > rfc3720). For iSCSI, SCSI timeout logic *must* be disabled until iSCSI > recovery is complete. This has actually been brought up when the scsi_times_out thread was going on. It kinda was at least. Some driver writers inluding sfnet used to play a lot of tricks with the timers to accomplish this (this was the goal for sfnet at least) and I do not think linux-scsi will allow it. Maybe that will change. host block/unblock logic in recent iSCSI transport > patch will help to implement that. > No it won't :( block/unblock does not disable timeouts it just makes it so new commands are not queued and they timeout when the driver knows that the transport is hosed.