From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: Warning - running *really* short on DMA buffers while doing file transfers Date: Fri, 27 Sep 2002 17:37:51 +0200 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20020927153751.GH23468@suse.de> References: <389902704.1033133455@aslan.scsiguy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: List-Id: linux-scsi@vger.kernel.org To: Matthew Jacob Cc: "Justin T. Gibbs" , "Pedro M. Rodrigues" , Mathieu Chouquet-Stringer , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org On Fri, Sep 27 2002, Matthew Jacob wrote: > > > If you don't like this behavior, which actually maximizes the > > throughput of the device, have the I/O scheduler hold back a single > > processes from creating such a large backlog. > > > Justin and I are (for once) in 100% agreement. Well Justin and you are both, it seems, missing the point. I'm now saying for the 3rd time, that there's zero problem in having a huge dirty cache backlog. This is not the problem, please disregard any reference to that. Count only the time spent for servicing a read request, _from when it enters the drive_ and until it completes. IO scheduler is _not_ involved. -- Jens Axboe