On Sat, Apr 20, 2024 at 04:58:11PM +0900, Damien Le Moal wrote: > A zone write plug BIO work function blk_zone_wplug_bio_work() calls > submit_bio_noacct_nocheck() to execute the next unplugged BIO. This > function may block. So executing zone plugs BIO works using the block > layer global kblockd workqueue can potentially lead to preformance or > latency issues as the number of concurrent work for a workqueue is > limited to WQ_DFL_ACTIVE (256). > 1) For a system with a large number of zoned disks, issuing write > requests to otherwise unused zones may be delayed wiating for a work > thread to become available. > 2) Requeue operations which use kblockd but are independent of zone > write plugging may alsoi end up being delayed. > > To avoid these potential performance issues, create a workqueue per > zoned device to execute zone plugs BIO work. The workqueue max active > parameter is set to the maximum number of zone write plugs allocated > with the zone write plug mempool. This limit is equal to the maximum > number of open zones of the disk and defaults to 128 for disks that do > not have a limit on the number of open zones. Looks good: Reviewed-by: Christoph Hellwig <hch@xxxxxx> Should the zone write plug submission do non-blocking submissions as well to avoid stalling in the workqueue thread all the time?
