Hi Jens On 11/9/18 12:06 AM, Jens Axboe wrote: > DM currently uses atomic inc/dec to maintain a busy count of > IO on a given device. For the dm-mq path, we can replace this > with helper that just checks the state of the tags on the device. > > First patch is a prep patch that allows the iteration helpers > to return true/false, like we support internally in sbitmap. > For a busy check we don't care about how many requests are > busy, just if some are or not. Hence we can stop iterating > tags as soon as we find one that is allocated.
If we don't care about how many requests are busy, why not check sb->map[idex].word directly ? It could be more efficient. Thanks Jianchao
