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block: skip elevator fields init for non-elv queue 

Don't init rq->hash and rq->rb_node in blk_mq_rq_ctx_init() if there is
no elevator. Also, move some other initialisers that imply barriers to
the end, so the compiler is free to rearrange and optimise other the
rest of them.

note: fold in a change from Jens leaving queue_list unconditional, as
it might lead to problems otherwise.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-10-18 21:37:27 +01:00 committed by Jens Axboe
parent 2ff0682da6
commit 4f266f2be8
1 changed files with 14 additions and 14 deletions
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28
block/blk-mq.c
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@ -325,6 +325,10 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
rq->internal_tag = BLK_MQ_NO_TAG;
}
if (blk_mq_need_time_stamp(rq))
rq->start_time_ns = ktime_get_ns();
else
rq->start_time_ns = 0;
/* csd/requeue_work/fifo_time is initialized before use */
rq->q = data->q;
rq->mq_ctx = data->ctx;
@ -334,41 +338,37 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
rq->rq_flags |= RQF_PM;
if (blk_queue_io_stat(data->q))
rq->rq_flags |= RQF_IO_STAT;
INIT_LIST_HEAD(&rq->queuelist);
INIT_HLIST_NODE(&rq->hash);
RB_CLEAR_NODE(&rq->rb_node);
rq->rq_disk = NULL;
rq->part = NULL;
#ifdef CONFIG_BLK_RQ_ALLOC_TIME
rq->alloc_time_ns = alloc_time_ns;
#endif
if (blk_mq_need_time_stamp(rq))
rq->start_time_ns = ktime_get_ns();
else
rq->start_time_ns = 0;
rq->io_start_time_ns = 0;
rq->stats_sectors = 0;
rq->nr_phys_segments = 0;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
rq->nr_integrity_segments = 0;
#endif
blk_crypto_rq_set_defaults(rq);
/* tag was already set */
WRITE_ONCE(rq->deadline, 0);
rq->timeout = 0;
rq->end_io = NULL;
rq->end_io_data = NULL;
data->ctx->rq_dispatched[op_is_sync(data->cmd_flags)]++;
blk_crypto_rq_set_defaults(rq);
INIT_LIST_HEAD(&rq->queuelist);
/* tag was already set */
WRITE_ONCE(rq->deadline, 0);
refcount_set(&rq->ref, 1);
if (!op_is_flush(data->cmd_flags) && (rq->rq_flags & RQF_ELV)) {
if (rq->rq_flags & RQF_ELV) {
struct elevator_queue *e = data->q->elevator;
rq->elv.icq = NULL;
if (e->type->ops.prepare_request) {
INIT_HLIST_NODE(&rq->hash);
RB_CLEAR_NODE(&rq->rb_node);
if (!op_is_flush(data->cmd_flags) &&
e->type->ops.prepare_request) {
if (e->type->icq_cache)
blk_mq_sched_assign_ioc(rq);