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From: Christoph Hellwig <hch@infradead.org>
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: dm-mpath: Work with blk multi-queue drivers
Date: Thu, 25 Sep 2014 09:08:23 -0700	[thread overview]
Message-ID: <20140925160823.GA3452@infradead.org> (raw)
In-Reply-To: <alpine.LRH.2.03.1409250923390.4696@AMR>

On Thu, Sep 25, 2014 at 09:57:41AM -0600, Keith Busch wrote:
> Thank you for all the background information. This definitely gives me
> a lot more to think about.
> 
> For my part, the goal was to change as little as possible to get basic
> blk-mq support working safely without regressing, and performance is
> not even on my radar yet. I purposefully did not try to understand the
> existing design well enough to propose re-arching. If we can address the
> 'request' life cycle management duality issue, would this be acceptable
> as a stopgap for blk-mq support?

I fully agree with going for the stop gap for now.  I tried going the
long way when I gave it a try and got stuck.

If people believe the get_request in the map path is harmful for the old
code we might have to make your change conditional just for blk-mq.  For
blk-mq request allocation never dips into the general purpose memory
pool, so it should be fine for that case.

  reply	other threads:[~2014-09-25 16:08 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-23 17:03 [PATCH] dm-mpath: Work with blk multi-queue drivers Keith Busch
2014-09-24  9:02 ` Hannes Reinecke
2014-09-24 14:27   ` Christoph Hellwig
2014-09-24 14:52 ` Christoph Hellwig
2014-09-24 17:20   ` Keith Busch
2014-09-24 18:34     ` Mike Snitzer
2014-09-24 18:48       ` Mike Snitzer
2014-09-25  0:13         ` Mike Snitzer
2014-09-25 15:57           ` Keith Busch
2014-09-25 16:08             ` Christoph Hellwig [this message]
2014-09-25 16:12             ` Mike Snitzer
2014-09-29 23:58               ` Junichi Nomura
2014-09-30 14:18                 ` Mike Snitzer
2014-09-30 23:43                   ` Junichi Nomura

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