On 2020/05/23 0:39, Hannes Reinecke wrote:
> When reclaiming zones we should arbitrate between the zoned
> devices to get a better throughput. So implement a simple
> round-robin load balancer between the zoned devices.
>
> Signed-off-by: Hannes Reinecke <h...@suse.de>
> ---
> drivers/md/dm-zoned-metadata.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c
> index 87784e7785bc..25dcad2a565f 100644
> --- a/drivers/md/dm-zoned-metadata.c
> +++ b/drivers/md/dm-zoned-metadata.c
> @@ -171,6 +171,8 @@ struct dmz_metadata {
> unsigned int nr_reserved_seq;
> unsigned int nr_chunks;
>
> + unsigned int last_alloc_idx;
> +
> /* Zone information array */
> struct xarray zones;
>
> @@ -2178,7 +2180,7 @@ struct dm_zone *dmz_alloc_zone(struct dmz_metadata
> *zmd, unsigned long flags)
> {
> struct list_head *list;
> struct dm_zone *zone;
> - unsigned int dev_idx = 0;
> + unsigned int dev_idx = zmd->last_alloc_idx;
>
> again:
> if (flags & DMZ_ALLOC_CACHE)
> @@ -2214,6 +2216,9 @@ struct dm_zone *dmz_alloc_zone(struct dmz_metadata
> *zmd, unsigned long flags)
> zone = list_first_entry(list, struct dm_zone, link);
> list_del_init(&zone->link);
>
> + if (!(flags & DMZ_ALLOC_CACHE))
> + zmd->last_alloc_idx = (dev_idx + 1) % zmd->nr_devs;
> +
> if (dmz_is_cache(zone))
> atomic_dec(&zmd->unmap_nr_cache);
> else if (dmz_is_rnd(zone))
> @@ -2839,6 +2844,7 @@ int dmz_ctr_metadata(struct dmz_dev *dev, int num_dev,
> zmd->dev = dev;
> zmd->nr_devs = num_dev;
> zmd->mblk_rbtree = RB_ROOT;
> + zmd->last_alloc_idx = 0;
> init_rwsem(&zmd->mblk_sem);
> mutex_init(&zmd->mblk_flush_lock);
> spin_lock_init(&zmd->mblk_lock);
>
OK. So my comment on patch 8 is already addressed. Or at least partly... Where
is last_alloc_idx actually used ? It looks like this only sets last_alloc_idx
but do not use that value on entry to dmz_alloc_zone() to allocate the zone.
--
Damien Le Moal
Western Digital Research
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