From: Jeff Garzik <jeff@garzik.org>
To: Mark Lord <liml@rtr.ca>
Cc: Daniel J Blueman <daniel.blueman@gmail.com>,
bzolnier@gmail.com, linux-ide@vger.kernel.org,
Linux Kernel <linux-kernel@vger.kernel.org>,
Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: Compact Flash performance...
Date: Thu, 31 May 2007 19:26:51 -0400 [thread overview]
Message-ID: <465F59BB.9040909@garzik.org> (raw)
In-Reply-To: <465F4ED0.10508@rtr.ca>
Mark Lord wrote:
> To maximize throughput, some kind of host-queuing would be needed,
> or just have the driver sit in a tight loop, starting the next I/O
> immediately when the previous one finishes. Linux isn't that quick (yet).
I was talking on IRC with Tejun just recently. There are several
controllers (and/or "situations") like this, where some amount of host
queueing would permit greater throughput, even when NCQ is not
supported. sata_sx4 is the most dramatic example, where host queueing
could potentially increase speed by a factor of 10 or more, since it is
penalized by an awful two-irq-per-command (w/ a per-host bottleneck to
boot) setup. Silicon Image has a "command buffer". And overall, I
designed ->qc_prep() hook separate from ->qc_issue() to enable the
prepartion of multiple commands such that it only takes a simple "go"
I/O to start a transaction, immediately after the previous one ends.
Jeff
next prev parent reply other threads:[~2007-05-31 23:26 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-30 22:10 Compact Flash performance Daniel J Blueman
2007-05-30 22:31 ` Lee Revell
2007-05-31 9:18 ` Daniel J Blueman
2007-05-30 22:56 ` Bartlomiej Zolnierkiewicz
2007-05-31 3:24 ` Mark Lord
2007-05-31 9:22 ` Daniel J Blueman
2007-05-31 12:22 ` Mark Lord
2007-05-31 17:25 ` Daniel J Blueman
2007-05-31 20:54 ` Mark Lord
2007-05-31 21:39 ` Daniel J Blueman
2007-05-31 22:33 ` Mark Lord
2007-05-31 22:35 ` Mark Lord
2007-05-31 22:37 ` Jeff Garzik
2007-05-31 22:43 ` Mark Lord
2007-06-02 5:10 ` Willy Tarreau
2007-05-31 23:47 ` Daniel J Blueman
2007-05-31 22:40 ` Mark Lord
2007-05-31 23:26 ` Jeff Garzik [this message]
[not found] <fa.XmtWMJk5gwBC00HJh+5O62Vx8eA@ifi.uio.no>
[not found] ` <fa.fl4+oXGwE5VC39h2DLdFoBUbqV4@ifi.uio.no>
[not found] ` <fa.+cW0LouEqSiZ6zrmBDeBJxRjPTg@ifi.uio.no>
[not found] ` <fa.PM7erd/Gm1gq8ZshwTBJwux7o6o@ifi.uio.no>
[not found] ` <fa.MYVClL+Q9g/jFTcUNWOeysiV0Ig@ifi.uio.no>
[not found] ` <fa.Q4zXu+xtMAT5H5vbl/zgxZk/Ivo@ifi.uio.no>
2007-06-01 0:00 ` Robert Hancock
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