From: James Bottomley <James.Bottomley@SteelEye.com>
To: Jeff Garzik <jgarzik@pobox.com>
Cc: Tejun Heo <htejun@gmail.com>,
ltuikov@yahoo.com, Luben Tuikov <luben_tuikov@adaptec.com>,
Albert Lee <albertcc@tw.ibm.com>,
linux-ide@vger.kernel.org,
SCSI Mailing List <linux-scsi@vger.kernel.org>,
Doug Maxey <dwm@maxeymade.com>
Subject: Re: [RFC] libata new EH document
Date: Thu, 01 Sep 2005 09:24:57 -0400 [thread overview]
Message-ID: <1125581097.4834.5.camel@mulgrave> (raw)
In-Reply-To: <20050901055421.GA23496@havoc.gtf.org>
On Thu, 2005-09-01 at 01:54 -0400, Jeff Garzik wrote:
> The long term direction for the SCSI core seems to be that of
> requiring auto-sensing.
No, I don't see the mid-layer error thread handling of this ever going
away.
> libata is simply being lazy: while the SCSI core continues to support
> kicking the EH thread when sense is missing, it's preferred for libata
> to reuse that infrastructure.
That makes the most sense ;-)
> Auto-sensing (and READ LOG EXT for NCQ errors) requires either an
> FSM or a kernel thread, to initiate a secondary qc for REQUEST SENSE.
> Since the common infrastructure already exists for this, libata reuses
> the existing SCSI EH kernel thread.
The current SCSI autosense in drivers doesn't require this because we
reuse the existing command that got the contingent allegiance condition.
This is the piece I'd like to get rid of because the extra fields and
extra setup to allow the command to be reused are a critical path hit.
If you look at any driver that does this (53c700.c for instance) you'll
see that the command is turned around and resubmitted in the irq
routine).
James
next prev parent reply other threads:[~2005-09-01 13:33 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-29 6:11 [RFC] libata new EH document Tejun Heo
2005-08-29 6:13 ` Tejun Heo
2005-08-30 9:10 ` Albert Lee
2005-08-30 10:26 ` Tejun Heo
2005-08-30 14:32 ` Luben Tuikov
2005-09-01 1:17 ` Tejun Heo
2005-09-01 2:22 ` Jeff Garzik
2005-09-01 2:42 ` Tejun Heo
2005-09-01 3:33 ` Luben Tuikov
2005-09-01 3:30 ` Luben Tuikov
2005-09-01 3:44 ` Tejun Heo
2005-09-01 4:38 ` Luben Tuikov
2005-09-01 5:44 ` Tejun Heo
2005-09-01 5:54 ` Jeff Garzik
2005-09-01 13:24 ` James Bottomley [this message]
2005-09-01 21:40 ` Luben Tuikov
2005-09-01 21:46 ` Jeff Garzik
2005-09-01 22:09 ` Luben Tuikov
2005-09-01 22:27 ` Jeff Garzik
2005-09-01 23:17 ` Luben Tuikov
2005-09-02 7:09 ` Stefan Richter
2005-09-01 22:22 ` Luben Tuikov
2005-09-01 22:31 ` Jeff Garzik
2005-09-01 21:55 ` James Bottomley
2005-09-01 22:07 ` Luben Tuikov
2005-09-01 22:23 ` James Bottomley
2005-09-01 22:36 ` Luben Tuikov
2005-09-01 23:01 ` James Bottomley
2005-09-01 23:03 ` Luben Tuikov
2005-09-01 23:27 ` Luben Tuikov
2005-09-01 2:22 ` Jeff Garzik
2005-08-30 14:27 ` James Bottomley
2005-09-07 8:25 ` Jeff Garzik
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