From: Bart Van Assche <[email protected]> commit 90b7198001f23ea37d3b46dc631bdaa2357a20b1 upstream.
elevator_get_default() uses the following algorithm to select an I/O scheduler from inside add_disk(): - In case of a single hardware queue or if sharing hardware queues across multiple request queues (BLK_MQ_F_TAG_HCTX_SHARED), use mq-deadline. - Otherwise, use 'none'. This is a good choice for most but not for all block drivers. Make it possible to override the selection of mq-deadline with a new flag, namely BLK_MQ_F_NO_SCHED_BY_DEFAULT. Cc: Christoph Hellwig <[email protected]> Cc: Ming Lei <[email protected]> Cc: Tetsuo Handa <[email protected]> Cc: Martijn Coenen <[email protected]> Cc: Jaegeuk Kim <[email protected]> Signed-off-by: Bart Van Assche <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jens Axboe <[email protected]> Signed-off-by: Wentao Zhang <[email protected]> --- block/elevator.c | 3 +++ include/linux/blk-mq.h | 6 ++++++ 2 files changed, 9 insertions(+) diff --git a/block/elevator.c b/block/elevator.c index 2f962662c32a..f762b2af1d2a 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -622,6 +622,9 @@ static inline bool elv_support_iosched(struct request_queue *q) */ static struct elevator_type *elevator_get_default(struct request_queue *q) { + if (q->tag_set && q->tag_set->flags & BLK_MQ_F_NO_SCHED_BY_DEFAULT) + return NULL; + if (q->nr_hw_queues != 1) return NULL; diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index f8ea27423d1d..39526279fbd3 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -398,7 +398,13 @@ enum { BLK_MQ_F_STACKING = 1 << 2, BLK_MQ_F_TAG_HCTX_SHARED = 1 << 3, BLK_MQ_F_BLOCKING = 1 << 5, + /* Do not allow an I/O scheduler to be configured. */ BLK_MQ_F_NO_SCHED = 1 << 6, + /* + * Select 'none' during queue registration in case of a single hwq + * or shared hwqs instead of 'mq-deadline'. + */ + BLK_MQ_F_NO_SCHED_BY_DEFAULT = 1 << 7, BLK_MQ_F_ALLOC_POLICY_START_BIT = 8, BLK_MQ_F_ALLOC_POLICY_BITS = 1, -- 2.31.1
-=-=-=-=-=-=-=-=-=-=-=- Links: You receive all messages sent to this group. View/Reply Online (#13669): https://lists.yoctoproject.org/g/linux-yocto/message/13669 Mute This Topic: https://lists.yoctoproject.org/mt/104880299/21656 Group Owner: [email protected] Unsubscribe: https://lists.yoctoproject.org/g/linux-yocto/unsub [[email protected]] -=-=-=-=-=-=-=-=-=-=-=-
