deadline-iosched: Introduce zone locking support
Introduce zone write locking to avoid write request reordering with zoned block devices. This is achieved using a finer selection of the next request to dispatch: 1) Any non-write request is always allowed to proceed. 2) Any write to a conventional zone is always allowed to proceed. 3) For a write to a sequential zone, the zone lock is first checked. a) If the zone is not locked, the write is allowed to proceed after its target zone is locked. b) If the zone is locked, the write request is skipped and the next request in the dispatch queue tested (back to step 1). For a write request that has locked its target zone, the zone is unlocked either when the request completes and the method deadline_request_completed() is called, or when the request is requeued using the method deadline_add_request(). Requests targeting a locked zone are always left in the scheduler queue to preserve the initial write order. If no write request can be dispatched, allow reads to be dispatched even if the write batch is not done. If the device used is not a zoned block device, or if zoned block device support is disabled, this patch does not modify deadline behavior. Signed-off-by:Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Reviewed-by:
Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
parent
c117bac7
Please register or sign in to comment