From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: "Nicholas A. Bellinger" <nab@linux-iscsi.org>,
Christoph Hellwig <hch@lst.de>
Cc: Christoph Hellwig <hch@infradead.org>,
"Nicholas A. Bellinger" <nab@daterainc.com>,
target-devel <target-devel@vger.kernel.org>,
linux-scsi <linux-scsi@vger.kernel.org>,
Hannes Reinecke <hare@suse.de>,
Mike Christie <michaelc@cs.wisc.edu>,
Sagi Grimberg <sagig@dev.mellanox.co.il>,
Andy Grover <agrover@redhat.com>,
Sagi Grimberg <sagig@mellanox.com>,
Mike Christie <mchristi@redhat.com>
Subject: Re: [PATCH-v2 2/2] target/iblock: Use -EAGAIN/-ENOMEM to propigate SAM BUSY/TASK_SET_FULL
Date: Mon, 07 Mar 2016 11:40:06 -0500 [thread overview]
Message-ID: <1457368806.632.18.camel@HansenPartnership.com> (raw)
In-Reply-To: <1457337836.10643.2.camel@haakon3.risingtidesystems.com>
On Mon, 2016-03-07 at 00:03 -0800, Nicholas A. Bellinger wrote:
> On Mon, 2016-03-07 at 08:55 +0100, Christoph Hellwig wrote:
> > On Sun, Mar 06, 2016 at 01:55:15PM -0800, Nicholas A. Bellinger
> > So as-is this might be well intended but either useless or broken.
> > --
>
> No, it useful for hosts that have an aggressive SCSI timeout, and it
> works as expected with Linux/SCSI hosts that either retry on BUSY
> status, or retry + reduce queue_depth on TASK_SET_FULL status.
I'm with Christoph on this: BUSY and QUEUE_FULL are already handled
generically in SCSI. All drivers should use the generics: to handle
separately, the driver has to intercept the error code, which I thought
I checked that none did (although it was a while ago). Additionally,
the timeout on these operations is retries * command timeout. So for
the default 5 retries and 30 seconds, you actually get to tolerate
BUSY/QUEUE_FULL for 2.5 minutes before you get an error. If this is a
problem, you can bump up the timer in
/sys/class/scsi_device/<id>/device/timeout
James
next prev parent reply other threads:[~2016-03-07 16:40 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-05 7:07 [PATCH-v2 1/2] target: Avoid DataIN transfers for non-GOOD SAM status Nicholas A. Bellinger
2016-03-05 7:07 ` [PATCH-v2 2/2] target/iblock: Use -EAGAIN/-ENOMEM to propigate SAM BUSY/TASK_SET_FULL Nicholas A. Bellinger
2016-03-05 21:01 ` Christoph Hellwig
2016-03-05 22:51 ` Nicholas A. Bellinger
2016-03-06 6:19 ` Christoph Hellwig
2016-03-06 21:55 ` Nicholas A. Bellinger
2016-03-07 7:55 ` Christoph Hellwig
2016-03-07 8:03 ` Nicholas A. Bellinger
2016-03-07 16:18 ` -EAGAIN and -ENOMEM from ->bi_end_io, was " Christoph Hellwig
2016-03-07 22:39 ` Nicholas A. Bellinger
2016-03-07 22:39 ` Nicholas A. Bellinger
2016-03-08 7:04 ` Christoph Hellwig
2016-03-07 16:40 ` James Bottomley [this message]
2016-03-07 22:44 ` Nicholas A. Bellinger
2016-03-05 21:01 ` [PATCH-v2 1/2] target: Avoid DataIN transfers for non-GOOD SAM status Christoph Hellwig
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