From: Jeff Garzik <jgarzik@pobox.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>, Mark Lord <liml@rtr.ca>
Cc: Tejun Heo <tj@kernel.org>,
IDE/ATA development list <linux-ide@vger.kernel.org>
Subject: Re: [PATCH] libata-core More robust parsing for multi_count(v5)
Date: Sun, 12 Apr 2009 11:31:16 -0400 [thread overview]
Message-ID: <49E20944.7070709@pobox.com> (raw)
In-Reply-To: <20090412161812.78e92948@lxorguk.ukuu.org.uk>
Alan Cox wrote:
>> The limit for sata_mv chipsets seems to actually be 7-sectors or less
>> for read/write multiple. Which means a max of 4 in practice.
>>
>> Similarly, we should also be preventing *any* PIO of more than one DRQ
>> for sata_mv. But I don't see a sensible way to do that either.
>
> Ugghhh..
Our infrastructure just flat doesn't deal well with per-xfer-mode sector
count limitations. It is quite easy for us to limit per-xfer sector
count on a __per device__ basis -- both SCSI and block layer handle that
well.
But deviating from that implies potentially having to re-merge (or
split) block layer requests -- IOW quickly moves into the non-trivial,
cross-stack category of problem.
Problem is, of course, sector count limits in ATA can be per-command (or
per-xfer-mode), not just per-device.
Jeff
next prev parent reply other threads:[~2009-04-12 15:31 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-18 14:26 [PATCH] libata-core Use more robust parsing for multi_count Mark Lord
2009-03-18 14:32 ` Alan Cox
2009-03-18 15:06 ` Mark Lord
2009-03-18 15:13 ` Mark Lord
2009-03-18 17:09 ` Alan Cox
2009-03-18 15:58 ` Mark Lord
2009-03-18 16:18 ` [PATCH] libata-core More robust parsing for multi_count(v3) Mark Lord
2009-03-18 16:24 ` Mark Lord
2009-03-19 0:23 ` Tejun Heo
2009-03-19 0:25 ` Tejun Heo
2009-03-19 17:30 ` [PATCH] libata-core More robust parsing for multi_count(v4) Mark Lord
2009-03-19 17:32 ` [PATCH] libata-core More robust parsing for multi_count(v5) Mark Lord
2009-03-19 23:33 ` Tejun Heo
2009-03-20 3:37 ` Mark Lord
2009-03-20 13:13 ` Mark Lord
2009-03-20 13:14 ` Mark Lord
2009-03-20 14:07 ` Alan Cox
2009-03-20 15:36 ` Mark Lord
2009-03-20 23:14 ` Tejun Heo
2009-03-21 0:54 ` Jeff Garzik
2009-03-21 2:17 ` Tejun Heo
2009-03-21 13:54 ` Mark Lord
2009-03-21 14:02 ` Alan Cox
2009-03-21 14:59 ` Mark Lord
2009-03-20 13:38 ` Alan Cox
2009-04-12 15:10 ` Mark Lord
2009-04-12 15:18 ` Alan Cox
2009-04-12 15:31 ` Jeff Garzik [this message]
2009-03-25 2:40 ` Jeff Garzik
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