From: Christoph Hellwig <hch@lst.de>
To: Mike Snitzer <snitzer@redhat.com>
Cc: Jens Axboe <axboe@fb.com>,
dm-devel@redhat.com, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 2/1] dm: do not allocate any mempools for blk-mq request-based DM
Date: Tue, 28 Apr 2015 08:28:43 +0200 [thread overview]
Message-ID: <20150428062843.GA19065@lst.de> (raw)
In-Reply-To: <20150428010303.GB31039@redhat.com>
On Mon, Apr 27, 2015 at 09:03:04PM -0400, Mike Snitzer wrote:
> Do not allocate the io_pool mempool for blk-mq request-based DM
> (DM_TYPE_MQ_REQUEST_BASED) in dm_alloc_rq_mempools().
>
> Also refine __bind_mempools() to have more precise awareness of which
> mempools each type of DM device uses -- avoids mempool churn when
> reloading DM tables (particularly for DM_TYPE_REQUEST_BASED).
Btw, I looked into this code and didn't dare to touch it before I
understood how we deal with the case of dm-mpath using blk-mq and
low level driver not or the other way around.
As far as I can see we'd need the request mempool as long as the
low level driver does not use dm-mq, independent of what dm-mpath
itsel uses.
The code doesn't seem to handle this right, but as mentioned I'm not
100% sure and need to dive deeper into this. Is there a place enforcing
dm-mpath is using the same request type as the underlying devices?
next prev parent reply other threads:[~2015-04-28 6:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-25 10:23 [PATCH v2] block, dm: don't copy bios for request clones Christoph Hellwig
2015-04-25 18:13 ` Hannes Reinecke
2015-04-26 13:35 ` Mike Snitzer
2015-04-26 14:20 ` Christoph Hellwig
2015-04-28 0:59 ` [PATCH v3] " Mike Snitzer
2015-04-28 1:03 ` [PATCH 2/1] dm: do not allocate any mempools for blk-mq request-based DM Mike Snitzer
2015-04-28 6:28 ` Christoph Hellwig [this message]
2015-04-28 10:22 ` Mike Snitzer
2015-04-28 5:49 ` [PATCH v3] block, dm: don't copy bios for request clones Hannes Reinecke
2015-04-28 6:29 ` Christoph Hellwig
2015-04-28 9:45 ` Mike Snitzer
2015-05-11 15:55 ` Mike Snitzer
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