From: Jens Axboe <axboe@suse.de>
To: James Bottomley <James.Bottomley@steeleye.com>
Cc: "Justin T. Gibbs" <gibbs@scsiguy.com>,
Matthew Jacob <mjacob@feral.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
Date: Fri, 27 Sep 2002 16:33:27 +0200 [thread overview]
Message-ID: <20020927143327.GG23468@suse.de> (raw)
In-Reply-To: <200209271426.g8REQ3228125@localhost.localdomain>
On Fri, Sep 27 2002, James Bottomley wrote:
> Therefore, it is in SCSI's interest to have the OS merge requests if it can
> purely from the transport efficiency point of view. Once we accept the
> necessity of having the OS do some elevator work it becomes detrimental to
> have this work repeated in the drive firmware.
Hear, hear. And given that the os io scheduler (I prefer to call it
that, elevator is pretty far from the truth :-) gets so close to drives
optimal performance in most cases, a small tag depth makes sense and
protects us from the latency concerns.
> I guess, however, that this issue will evaporate substantially once
> the aic7xxx driver uses ordered tags to represent the transaction
> integrity since the barriers will force the drive seek algorithm to
> follow the tag transmission order much more closely.
Depends on how often you issue these ordered tags, but yes I hope so
too.
--
Jens Axboe
next prev parent reply other threads:[~2002-09-27 14:33 UTC|newest]
Thread overview: 81+ 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
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 14:26 ` James Bottomley
2002-09-27 14:33 ` Jens Axboe [this message]
2002-09-27 16:26 ` Justin T. Gibbs
2002-09-27 17:21 ` James Bottomley
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 19:36 ` Andrew Morton
2002-09-27 19:52 ` Justin T. Gibbs
2002-09-27 19:52 ` Justin T. Gibbs
2002-09-27 21:13 ` James Bottomley
2002-09-27 21:13 ` James Bottomley
2002-09-27 21:18 ` Matthew Jacob
2002-09-27 21:18 ` Matthew Jacob
2002-09-27 21:23 ` James Bottomley
2002-09-27 21:23 ` James Bottomley
2002-09-27 21:29 ` Justin T. Gibbs
2002-09-27 21:29 ` Justin T. Gibbs
2002-09-27 21:32 ` Matthew Jacob
2002-09-27 21:32 ` Matthew Jacob
2002-09-27 22:08 ` Mike Anderson
2002-10-01 0:07 ` Doug Ledford
2002-10-01 0:13 ` Doug Ledford
2002-09-30 23:49 ` Doug Ledford
2002-09-27 21:28 ` Justin T. Gibbs
2002-09-27 21:28 ` Justin T. Gibbs
2002-09-28 15:52 ` James Bottomley
2002-09-28 15:52 ` James Bottomley
2002-09-28 23:25 ` Luben Tuikov
2002-09-28 23:25 ` Luben Tuikov
2002-09-29 2:48 ` James Bottomley
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 4:00 ` Justin T. Gibbs
2002-09-29 15:45 ` James Bottomley
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 19:06 ` Luben Tuikov
2002-09-30 23:54 ` Doug Ledford
2002-09-27 19:58 ` Andrew Morton
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 18:29 ` Rik van Riel
2002-09-27 14:56 ` 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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