From: Jens Axboe <axboe@suse.de>
To: "Justin T. Gibbs" <gibbs@scsiguy.com>
Cc: "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
Date: Fri, 27 Sep 2002 08:13:28 +0200 [thread overview]
Message-ID: <20020927061328.GL5646@suse.de> (raw)
In-Reply-To: <3870780000.1033054272@aslan.scsiguy.com>
On Thu, Sep 26 2002, Justin T. Gibbs wrote:
> > I reported this same problem some weeks ago -
> > http://marc.theaimsgroup.com/?l=linux-kernel&m=103069116227685&w=2 .
> > 2.4.20pre kernels solved the error messages flooding the console, and
> > improved things a bit, but system load still got very high and disk read
> > and write performance was lousy. Adding more memory and using a
> > completely different machine didn't help. What did? Changing the Adaptec
> > scsi driver to aic7xxx_old . The performance was up 50% for writes and
> > 90% for reads, and the system load was acceptable. And i didn't even had
> > to change the RedHat kernel (2.4.18-10) for a custom one. The storage was
> > two external Arena raid boxes, btw.
>
> I would be interested in knowing if reducing the maximum tag depth for
> the driver improves things for you. There is a large difference in the
> defaults between the two drivers. It has only reacently come to my
> attention that the SCSI layer per-transaction overhead is so high that
> you can completely starve the kernel of resources if this setting is too
> high. For example, a 4GB system installing RedHat 7.3 could not even
> complete an install on a 20 drive system with the default of 253 commands.
> The latest version of the aic7xxx driver already sent to Marcelo drops the
> default to 32.
2.4 layer is most horrible there, 2.5 at least gets rid of the old
scsi_dma crap. That said, 253 default depth is a bit over the top, no?
--
Jens Axboe, who always uses 4
next prev parent reply other threads:[~2002-09-27 6:08 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-26 3:27 Warning - running *really* short on DMA buffers while doing file transfers Mathieu Chouquet-Stringer
2002-09-26 6:14 ` Jens Axboe
2002-09-26 7:04 ` Pedro M. Rodrigues
2002-09-26 15:31 ` Justin T. Gibbs
2002-09-27 6:13 ` Jens Axboe [this message]
2002-09-27 6:33 ` Matthew Jacob
2002-09-27 6:36 ` Jens Axboe
2002-09-27 6:50 ` Matthew Jacob
2002-09-27 6:56 ` Jens Axboe
2002-09-27 7:18 ` Matthew Jacob
2002-09-27 7:24 ` Jens Axboe
2002-09-27 7:29 ` Matthew Jacob
2002-09-27 7:34 ` Matthew Jacob
2002-09-27 7:45 ` Jens Axboe
2002-09-27 8:37 ` Matthew Jacob
2002-09-27 10:25 ` Jens Axboe
2002-09-27 12:18 ` Matthew Jacob
2002-09-27 12:54 ` Jens Axboe
2002-09-27 13:30 ` Justin T. Gibbs
2002-09-27 14:26 ` James Bottomley
2002-09-27 14:33 ` Jens Axboe
2002-09-27 16:26 ` Justin T. Gibbs
2002-09-27 17:21 ` James Bottomley
2002-09-27 18:56 ` Justin T. Gibbs
2002-09-27 19:07 ` Warning - running *really* short on DMA buffers while doingfile transfers Andrew Morton
2002-09-27 19:16 ` Justin T. Gibbs
2002-09-27 19:36 ` Warning - running *really* short on DMA buffers while doingfiletransfers Andrew Morton
2002-09-27 19:52 ` Justin T. Gibbs
2002-09-27 21:13 ` James Bottomley
2002-09-27 21:18 ` Matthew Jacob
2002-09-27 21:23 ` James Bottomley
2002-09-27 21:29 ` Justin T. Gibbs
2002-09-27 21:32 ` Matthew Jacob
2002-09-27 22:08 ` Mike Anderson
2002-09-30 23:49 ` Doug Ledford
2002-09-27 21:28 ` Justin T. Gibbs
2002-09-28 15:52 ` James Bottomley
2002-09-28 23:25 ` Luben Tuikov
2002-09-29 2:48 ` James Bottomley
2002-09-30 8:34 ` Jens Axboe
2002-09-29 4:00 ` Justin T. Gibbs
2002-09-29 15:45 ` James Bottomley
2002-09-29 16:49 ` [ getting OT ] " Matthew Jacob
2002-09-30 19:06 ` Luben Tuikov
2002-09-30 23:54 ` Doug Ledford
2002-09-27 19:58 ` Andrew Morton
2002-09-27 20:58 ` Warning - running *really* short on DMA buffers while doing file transfers Justin T. Gibbs
2002-09-27 21:38 ` Patrick Mansfield
2002-09-27 22:08 ` Justin T. Gibbs
2002-09-27 22:28 ` Patrick Mansfield
2002-09-27 22:48 ` Justin T. Gibbs
2002-09-27 18:59 ` Warning - running *really* short on DMA buffers while doingfile transfers Andrew Morton
2002-09-27 14:30 ` Warning - running *really* short on DMA buffers while doing file transfers Jens Axboe
2002-09-27 17:19 ` Justin T. Gibbs
2002-09-27 18:29 ` Rik van Riel
2002-09-27 14:56 ` Rik van Riel
2002-09-27 15:34 ` Matthew Jacob
2002-09-27 15:37 ` Jens Axboe
2002-09-27 17:20 ` Justin T. Gibbs
2002-09-27 12:28 ` Pedro M. Rodrigues
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