[dm-devel] [PATCH 11/12] dm-zoned: round-robin load balancer for reclaiming zones

[Hannes Reinecke]

On 5/25/20 4:42 AM, Damien Le Moal wrote:
> 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 <hare at 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.
> 
Aw, fsck. Something went astray when generating the patches.
Will be fixing it up for the next round.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke            Teamlead Storage & Networking
hare at suse.de                               +49 911 74053 688
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