From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: calling scsi_adjust_queue_depth() during I/O... Date: Fri, 5 Aug 2005 17:59:06 +0200 Message-ID: <20050805155905.GU5561@suse.de> References: <20050804234155.GJ13374@plap.qlogic.org> <20050805075751.GN9369@suse.de> <20050805110911.GA22867@htj.dyndns.org> <42F350E6.2090109@gmail.com> <20050805123301.GA3311@htj.dyndns.org> <20050805155548.GP13374@plap.qlogic.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from ns.virtualhost.dk ([195.184.98.160]:15770 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S261872AbVHEP5I (ORCPT ); Fri, 5 Aug 2005 11:57:08 -0400 Content-Disposition: inline In-Reply-To: <20050805155548.GP13374@plap.qlogic.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Andrew Vasquez Cc: Tejun Heo , Linux-SCSI Mailing List On Fri, Aug 05 2005, Andrew Vasquez wrote: > On Fri, 05 Aug 2005, Tejun Heo wrote: > > > > Oops, forget about the previous mail. Above patch make it into the > > > tree and it's the source of the problem. My git HEAD was pointing at > > > the latest update but I haven't updated my cache, so I was looking at > > > the old source tree. My apologies for the hassle and the bug. > > > > > > Original code was broken in the following two points. > > > > > > * tag_index wasn't allocated fully > > > * tag_map's extra bits were always initialized w/ 1's. > > > > > > The first bug is critical and the second bug prevents proper enlarging > > > of tag map. However, the second bug effectively masks the first bug > > > avoiding critical problem. My above mentioned patch broke things > > > seriously when reducing tag size on flight. > > > > > > Again, my apologies and patch will soon follow. > > > > Here's the fix. It basically revives bqt->real_max_depth sans > > allocation optimization in init_tag_map. I've also added a comment > > explicitly noting that tag map cannot be shrunk to prevent other > > morons like me. :-( Please try this one and let me know how it works. > > If this is the correct fix, I'll repost properly to Jens and lkml with > > detailed explanation on how it was broken in the original code and how > > I broke it with my previous patch. Sorry. > > OK, 20 minutes into lowering and raising the queue-depth and > everything appears to be working fine. I'll continue banging away > with my configuration and let you know if anything else comes up. > Looks good so far. Thanks for fixing it so quickly, Tejun! I'll be on vacation next week, can you make sure it gets to Andrew? -- Jens Axboe