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? > 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@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
