On 2020/05/21 3:53, Mike Snitzer wrote: > On Tue, May 19 2020 at 6:36pm -0400, > Damien Le Moal <Damien.LeMoal@xxxxxxx> 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@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
