From: Hannes Reinecke <hare@suse.de>
To: Keith Busch <keith.busch@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Jun'ichi Nomura <j-nomura@ce.jp.nec.com>,
dm-devel@redhat.com, Mike Snitzer <snitzer@redhat.com>
Subject: Re: [PATCHv2 0/4] blk-mq support for dm multipath
Date: Tue, 28 Oct 2014 19:48:41 +0100 [thread overview]
Message-ID: <544FE509.3020207@suse.de> (raw)
In-Reply-To: <alpine.LNX.2.00.1410281808390.4225@localhost.lm.intel.com>
On 10/28/2014 07:13 PM, Keith Busch wrote:
> No comments this time. Did I totally botch this in the wrong direction,
> or was the timing bad with the linux con/plumbers that week?
>
Basically the latter. We (ie hch and myself) discussed this briefly at
LPC, and thought it'd be the right step in the right direction.
'Real' multipath support w/ blk-mq would need some more thought, though.
What we've been discussing was to redo the entire I/O submission path:
a) pass down I/O _without_ cloning on the current path
b) clone the request _for retry_ only.
with b) covering retry on a different path and partial I/O submission
on the current path.
That would have the benefit doing away with the current request/bio
cloning. Plus we could even model things like 'preferred' path.
Now we only need someone to implement this ...
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
prev parent reply other threads:[~2014-10-28 18:48 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-17 23:46 [PATCHv2 0/4] blk-mq support for dm multipath Keith Busch
2014-10-17 23:46 ` [PATCHv2 1/4] dm: prep initialized requests Keith Busch
2014-10-17 23:46 ` [PATCHv2 2/4] dm: Submit stacked requests in irq enabled context Keith Busch
2014-10-17 23:46 ` [PATCHv2 3/4] dm: Move request allocation to dm_target type Keith Busch
2014-10-17 23:46 ` [PATCHv2 4/4] block: blk-mq support for cloned requests Keith Busch
2014-10-28 18:13 ` [PATCHv2 0/4] blk-mq support for dm multipath Keith Busch
2014-10-28 18:26 ` Mike Snitzer
2014-12-05 23:25 ` Mike Snitzer
2014-12-05 23:33 ` Keith Busch
2014-12-06 0:35 ` Mike Snitzer
2014-12-06 5:53 ` Mike Snitzer
2014-12-06 6:09 ` Mike Snitzer
2014-12-13 2:08 ` Mike Snitzer
2014-10-28 18:48 ` Hannes Reinecke [this message]
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