On Wed, 2020-05-27 at 08:22 +0200, Hannes Reinecke wrote: > Prefer full zones when selecting the next zone for reclaim. > > Signed-off-by: Hannes Reinecke <[email protected]> > --- > drivers/md/dm-zoned-metadata.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c > index b89b3d3b9ec9..f161ef4e3d3d 100644 > --- a/drivers/md/dm-zoned-metadata.c > +++ b/drivers/md/dm-zoned-metadata.c > @@ -1936,7 +1936,7 @@ static struct dm_zone > *dmz_get_rnd_zone_for_reclaim(struct dmz_metadata *zmd, > unsigned int idx, bool idle) > { > struct dm_zone *dzone = NULL; > - struct dm_zone *zone; > + struct dm_zone *zone, *last = NULL; > struct list_head *zone_list; > > /* If we have cache zones select from the cache zone list */ > @@ -1953,6 +1953,13 @@ static struct dm_zone > *dmz_get_rnd_zone_for_reclaim(struct dmz_metadata *zmd, > dzone = zone->bzone; > if (dzone->dev->dev_idx != idx) > continue; > + if (!last) { > + last = dzone; > + continue; > + } > + if (last->weight < dzone->weight) > + continue; > + dzone = last; > } else > dzone = zone; > if (dmz_lock_zone_reclaim(dzone))
If all random/cache zones are used but none of them satisfy the condition last->weight < dzone->weight, we may end up starving reclaim and having user IOs accessing a new chunk wait a loooong time, if not forever, No ? I agree that aiming at reclaim of full zones first is more efficient, but we need a fallback to ensure forward progress. -- Damien Le Moal Western Digital Research -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
