From: "Jörn Engel" <joern@logfs.org>
To: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>,
James Bottomley <jbottomley@parallels.com>,
linux-scsi@vger.kernel.org, Ewan Milne <emilne@redhat.com>,
James Smart <james.smart@emulex.com>,
Ren Mingxin <renmx@cn.fujitsu.com>,
Roland Dreier <roland@purestorage.com>,
Bryn Reeves <bmr@redhat.com>
Subject: Re: [PATCH 3/9] scsi: improved eh timeout handler
Date: Mon, 10 Jun 2013 11:19:16 -0400 [thread overview]
Message-ID: <20130610151916.GA18076@logfs.org> (raw)
In-Reply-To: <51B595C1.8040106@suse.de>
On Mon, 10 June 2013 11:00:49 +0200, Hannes Reinecke wrote:
> On 06/10/2013 10:20 AM, Christoph Hellwig wrote:
> >
> > Why can't we use a work item per command? Linking things into a list
> > just to queue it up to workqueues missed half of the point of the
> > workqueue infrastructure.
> >
> Hmm. I felt that using a per command workqueue might be a bit excessive.
> Also the current semantics call for a synchronous command abort.
> So even using a per command workqueue won't buy us anything as the
> workqueue item would have to wait for the command abort to complete,
> which again is quite a waste.
Not sure if you confuse workqueue with workitem. Either way, using a
single work item to handle a queue of commands does not fly and we
either have to use per-command work items or abandon work queues and
use a kernel thread. The middle ground is either racy or useless.
I don't care too much whether we use per-command work items or a
single system-global thread. This shouldn't ever become a hot path or
the system is screwed anyway. The only problem with our current error
handling is that even rare errors can effectively break the system.
Jörn
--
Victory in war is not repetitious.
-- Sun Tzu
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next prev parent reply other threads:[~2013-06-10 16:48 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-10 7:40 [PATCHv2 0/9] New SCSI command timeout handler Hannes Reinecke
2013-06-10 7:40 ` [PATCH 1/9] scsi: move initialization of scmd->eh_entry Hannes Reinecke
2013-06-10 8:17 ` Christoph Hellwig
2013-06-10 7:40 ` [PATCH 2/9] blk-timeout: add BLK_EH_SCHEDULED return code Hannes Reinecke
2013-06-10 7:40 ` [PATCH 3/9] scsi: improved eh timeout handler Hannes Reinecke
2013-06-10 8:20 ` Christoph Hellwig
2013-06-10 9:00 ` Hannes Reinecke
2013-06-10 15:19 ` Jörn Engel [this message]
2013-06-10 23:24 ` Jörn Engel
2013-06-11 6:18 ` Hannes Reinecke
2013-06-11 16:35 ` Jörn Engel
2013-06-11 18:57 ` James Bottomley
2013-06-11 20:41 ` Ewan Milne
2013-06-11 20:54 ` James Bottomley
2013-06-12 5:54 ` Hannes Reinecke
2013-06-12 6:34 ` Bart Van Assche
2013-06-12 6:42 ` Hannes Reinecke
2013-06-10 15:47 ` Jörn Engel
2013-06-10 7:40 ` [PATCH 4/9] virtio_scsi: Enable new EH " Hannes Reinecke
2013-06-12 14:54 ` Paolo Bonzini
2013-06-13 1:58 ` Asias He
2013-06-10 7:40 ` [PATCH 5/9] virtio-scsi: Implement TMF timeout Hannes Reinecke
2013-06-12 14:54 ` Paolo Bonzini
2013-06-13 1:58 ` Asias He
2013-06-10 7:40 ` [PATCH 6/9] libsas: Enable new EH timeout handler Hannes Reinecke
2013-06-10 7:40 ` [PATCH 7/9] mptsas: " Hannes Reinecke
2013-06-10 7:40 ` [PATCH 8/9] mpt2sas: " Hannes Reinecke
2013-06-10 15:31 ` Jörn Engel
2013-06-11 5:41 ` Hannes Reinecke
2013-06-10 7:40 ` [PATCH 9/9] mpt3sas: " Hannes Reinecke
-- strict thread matches above, loose matches on Subject: below --
2013-07-01 14:24 [PATCHv3 0/9] New EH command " Hannes Reinecke
2013-07-01 14:24 ` [PATCH 3/9] scsi: improved eh " Hannes Reinecke
2013-08-22 8:51 ` Ren Mingxin
2013-08-23 12:27 ` Hannes Reinecke
2013-08-29 13:32 [PATCHv4 0/9] New EH command " Hannes Reinecke
2013-08-29 13:32 ` [PATCH 3/9] scsi: improved eh " Hannes Reinecke
2013-09-02 7:12 [PATCHv5 0/9] New EH command " Hannes Reinecke
2013-09-02 7:12 ` [PATCH 3/9] scsi: improved eh " Hannes Reinecke
2013-09-02 12:45 ` Bart Van Assche
2013-09-02 13:11 ` Hannes Reinecke
2013-09-02 16:38 ` Bart Van Assche
2013-09-03 9:13 ` Bart Van Assche
2013-09-04 7:02 ` Hannes Reinecke
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