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Date: Fri, 27 Sep 2002 17:37:51 +0200
From: Jens Axboe <axboe@suse.de>
To: Matthew Jacob <mjacob@feral.com>
Cc: "Justin T. Gibbs" <gibbs@scsiguy.com>,
       "Pedro M. Rodrigues" <pmanuel@myrealbox.com>,
       Mathieu Chouquet-Stringer <mathieu@newview.com>,
       linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Warning - running *really* short on DMA buffers while doing file transfers
Message-ID: <20020927153751.GH23468@suse.de>
References: <389902704.1033133455@aslan.scsiguy.com> <Pine.BSF.4.21.0209270833450.21876-100000@beppo>
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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