Re: [dm-devel] [PATCHv2 0/6] dm-zoned: improve cache performance
On 2020/05/21 3:53, Mike Snitzer wrote: > On Tue, May 19 2020 at 6:36pm -0400, > Damien Le Moal wrote: > >> On 2020/05/19 17:14, 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. >> >> I ran this overnight with no problems. Throughput results attached. >> Reclaim seems to be a little too aggressive as it triggers very early. But we >> can tune that later if really needed: the combination of ext4 writing all >> over >> the place and the faster cache zones on SSD may simply result in a >> percentage of >> free cache zones becoming low very quickly, in which case, reclaim is working >> exactly as expected :) > > I've staged this series for 5.8 in linux-next > > Just to make sure no regressions due to all the metadata2 changes: Did > you happen to verify all worked as expected without using an extra > drive? Yes, I did. Single and dual drive both work fine with v2 metadata. I will retest the case of a V1 format using V2 code to be extra sure. > >> Mike, >> >> With the NVMe io_opt fix patch applied, the alignment warning for the target >> limits is gone. > > OK > > Thanks, > Mike > > -- Damien Le Moal Western Digital Research -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
Re: [dm-devel] [PATCHv2 0/6] dm-zoned: improve cache performance
On Tue, May 19 2020 at 6:36pm -0400, Damien Le Moal wrote: > On 2020/05/19 17:14, 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. > > I ran this overnight with no problems. Throughput results attached. > Reclaim seems to be a little too aggressive as it triggers very early. But we > can tune that later if really needed: the combination of ext4 writing all over > the place and the faster cache zones on SSD may simply result in a percentage > of > free cache zones becoming low very quickly, in which case, reclaim is working > exactly as expected :) I've staged this series for 5.8 in linux-next Just to make sure no regressions due to all the metadata2 changes: Did you happen to verify all worked as expected without using an extra drive? > Mike, > > With the NVMe io_opt fix patch applied, the alignment warning for the target > limits is gone. OK Thanks, Mike -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
Re: [dm-devel] [PATCHv2 0/6] dm-zoned: improve cache performance
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 -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
[dm-devel] [PATCHv2 0/6] dm-zoned: improve cache performance
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 - 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() drivers/md/dm-zoned-metadata.c | 140 ++--- drivers/md/dm-zoned-reclaim.c | 109 drivers/md/dm-zoned-target.c | 19 -- drivers/md/dm-zoned.h | 13 +++- 4 files changed, 196 insertions(+), 85 deletions(-) -- 2.16.4 -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
