Re: [PATCH 4/6] dm-zoned: start reclaim with sequential zones

[Damien Le Moal <Damien.LeMoal@wdc.com>]

On 2020/05/19 17:14, Hannes Reinecke wrote:
> Sequential zones perform better for reclaim, so start off using
> them and only use random zones as a fallback when cache zones are
> present.
> 
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
>  drivers/md/dm-zoned-reclaim.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/md/dm-zoned-reclaim.c b/drivers/md/dm-zoned-reclaim.c
> index 1855c056d6a4..1283405bec29 100644
> --- a/drivers/md/dm-zoned-reclaim.c
> +++ b/drivers/md/dm-zoned-reclaim.c
> @@ -281,15 +281,16 @@ static int dmz_reclaim_rnd_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
>  	struct dm_zone *szone = NULL;
>  	struct dmz_metadata *zmd = zrc->metadata;
>  	int ret;
> -	int alloc_flags = dmz_nr_cache_zones(zmd) ?
> -		DMZ_ALLOC_RND : DMZ_ALLOC_SEQ;
> +	int alloc_flags = DMZ_ALLOC_SEQ;
>  
> -	/* Always use sequential zones to reclaim random zones */
> -	if (dmz_is_rnd(dzone))
> -		alloc_flags = DMZ_ALLOC_SEQ;
>  	/* Get a free random or sequential zone */
>  	dmz_lock_map(zmd);
> +again:
>  	szone = dmz_alloc_zone(zmd, alloc_flags | DMZ_ALLOC_RECLAIM);
> +	if (!szone && alloc_flags == DMZ_ALLOC_SEQ && dmz_nr_cache_zones(zmd)) {
> +		alloc_flags = DMZ_ALLOC_RND;
> +		goto again;
> +	}
>  	dmz_unlock_map(zmd);
>  	if (!szone)
>  		return -ENOSPC;
> 

Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>

-- 
Damien Le Moal
Western Digital Research