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 :) Mike, With the NVMe io_opt fix patch applied, the alignment warning for the target limits is gone. For the entire series: Tested-by: Damien Le Moal <damien.lemoal@xxxxxxx> > > 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(-) > -- Damien Le Moal Western Digital Research
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