block: prefetch request to be initialized

Now we have the tags available in __blk_mq_alloc_requests_batch(), we
can start fetching the first request cacheline before calling into the
request initialization.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20211019153300.623322-4-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index e881e12a2691eaa82fbcd21267e374c505a1bbc2..7cdb10f96aa6cb224a326098b015497bd11eb083 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -405,6 +405,7 @@ __blk_mq_alloc_requests_batch(struct blk_mq_alloc_data *data,
        for (i = 0; tag_mask; i++) {
                if (!(tag_mask & (1UL << i)))
                        continue;
+               prefetch(tags->static_rqs[tag]);
                tag = tag_offset + i;
                tag_mask &= ~(1UL << i);
                rq = blk_mq_rq_ctx_init(data, tags, tag, alloc_time_ns);