From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: blk-mq DM changes for 3.20 [was: Re: blk-mq request allocation stalls] Date: Wed, 28 Jan 2015 10:49:27 -0700 Message-ID: <54C92127.4030408@kernel.dk> References: <54B3F78D.2020704@kernel.dk> <54B3FE89.200@sandisk.com> <54B3FFAE.4070609@kernel.dk> <54B40E8A.6010005@kernel.dk> <54B532EE.20700@kernel.dk> <20150127184258.GB2078@redhat.com> <54C91172.10002@kernel.dk> <20150128174442.GA11951@redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150128174442.GA11951@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Mike Snitzer Cc: Keith Busch , Bart Van Assche , device-mapper development , Jun'ichi Nomura , Christoph Hellwig List-Id: dm-devel.ids On 01/28/2015 10:44 AM, Mike Snitzer wrote: > On Wed, Jan 28 2015 at 11:42am -0500, > Jens Axboe wrote: > >> On 01/27/2015 11:42 AM, Mike Snitzer wrote: >>> Hey Jens, >>> >>> I _think_ we've resolved the issues Bart raised for request-based DM's >>> support for blk-mq devices (anything remaining seems specific to iSER's >>> blk-mq support which is in development). Though Keith did have that one >>> additional patch for that block scatter gather attribute that we still >>> need to review closer. >>> >>> Anyway, I think what we have is a solid start and see no reason to hold >>> these changes back further. So I've rebased the 'dm-for-3.20' branch of >>> linux-dm.git ontop of 3.19-rc6 and reordered the required block changes >>> to be at the front of the series, see: >>> https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/log/?h=dm-for-3.20 >>> >>> (these changes have been in Linux next for a month, via linux-dm.git >>> 'for-next') >>> >>> With your OK, I'd be happy to carry the required block changes and >>> ultimately request Linus pull them for 3.20 (I can backfill your Acks if >>> you approve). BUT I also have no problem with you picking up the block >>> changes to submit via your block tree (I'd just have to rebase ontop of >>> your 3.20 branch once you pull them in). >> >> I'd prefer to take these prep patches through the block tree. > > Great, should I send the patches or can you cherry-pick? I already cherry picked them, they are in the for-3.20/core branch. >> Only one I don't really like is this one: >> >> https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-for-3.20&id=23556c2461407495099d1eb20b0de43432dc727d >> >> I prefer keeping the alloc path as lean as possible, normal allocs >> always initialize ->bio since they need to associate a bio with it. > > Would be very surprised if this initialization were measurable but.. That's what people always say, and then keep piling more crap in... > I could push this initialization into the DM-mpath driver (just after > blk_get_request, like Keith opted for) but that seemed really gross. It's already doing blk_rq_init() now, so not a huge change and not that nasty. -- Jens Axboe