From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: Re: [PATCHv2 0/6] dm-zoned: improve cache performance Date: Tue, 19 May 2020 13:36:56 -0400 Message-ID: <20200519173655.GA30916@redhat.com> References: <20200519081424.103318-1-hare@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20200519081424.103318-1-hare@suse.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com Content-Disposition: inline To: Hannes Reinecke Cc: Damien LeMoal , dm-devel@redhat.com List-Id: dm-devel.ids On Tue, May 19 2020 at 4:14am -0400, Hannes Reinecke wrote: > Hi all, > > here's an update to dm-zoned to separate out cache zones. > In the update to metadata version 2 the regular drive was split > in emulated zones, which were handled just like 'normal' random > write zones. > This causes a performance drop once these emulated zones have > been mapped, as typicall the random zones from the zoned drive > will perform noticeably slower than those from the regular drive. > (After all, that was kinda the idea of using a regular disk in > the first place ...) > > So in this patchset I've introduced a separate 'cache' zone type, > allowing us to differentiate between emulated and real zones. > With that we can switch the allocation mode to use only cache > zones, and use random zones similar to sequential write zones. > That avoids the performance issue noted above. > > I've also found that the sequential write zones perform noticeably > better on writes (which is all we're caching anyway), so I've > added another patch switching the allocation routine from preferring > sequential write zones for reclaim. > > This patchset also contains some minor fixes like remving an unused > variable etc. > > As usual, comments and reviews are welcome. > > Changes to v1: > - Include reviews from Damien I'll take a look at this series now, but I'm still waiting for formal Reviewed-by: or Acked-by: from Damien before I'll stage for 5.8 -- current development window is coming to a close though. > - Introduce allocation flags > - Terminate reclaim on contention > - Rework original patch series > > Hannes Reinecke (6): > dm-zoned: return NULL if dmz_get_zone_for_reclaim() fails to find a zone > dm-zoned: separate random and cache zones > dm-zoned: reclaim random zones when idle > dm-zoned: start reclaim with sequential zones > dm-zoned: terminate reclaim on congestion > dm-zoned: remove unused variable in dmz_do_reclaim() FYI I folded the last 6/6 patch back into the original commit that introduced the unused variable (via rebase). Thanks, Mike