From 8d663f34f8afcf5fc6a84c3cc4fa28cc84d58e39 Mon Sep 17 00:00:00 2001 From: Lin Feng Date: Thu, 15 Apr 2021 11:39:20 +0800 Subject: blk-mq: bypass IO scheduler's limit_depth for passthrough request Commit 01e99aeca39796003 ("blk-mq: insert passthrough request into hctx->dispatch directly") gives high priority to passthrough requests and bypass underlying IO scheduler. But as we allocate tag for such request it still runs io-scheduler's callback limit_depth, while we really want is to give full sbitmap-depth capabity to such request for acquiring available tag. blktrace shows PC requests(dmraid -s -c -i) hit bfq's limit_depth: 8,0 2 0 0.000000000 39952 1,0 m N bfq [bfq_limit_depth] wr_busy 0 sync 0 depth 8 8,0 2 1 0.000008134 39952 D R 4 [dmraid] 8,0 2 2 0.000021538 24 C R [0] 8,0 2 0 0.000035442 39952 1,0 m N bfq [bfq_limit_depth] wr_busy 0 sync 0 depth 8 8,0 2 3 0.000038813 39952 D R 24 [dmraid] 8,0 2 4 0.000044356 24 C R [0] This patch introduce a new wrapper to make code not that ugly. Signed-off-by: Lin Feng Reviewed-by: Ming Lei Link: https://lore.kernel.org/r/20210415033920.213963-1-linf@wangsu.com Signed-off-by: Jens Axboe --- block/blk-mq.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'block/blk-mq.c') diff --git a/block/blk-mq.c b/block/blk-mq.c index d4d7c1caa439..927189a55575 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -361,11 +361,12 @@ static struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data) if (e) { /* - * Flush requests are special and go directly to the + * Flush/passthrough requests are special and go directly to the * dispatch list. Don't include reserved tags in the * limiting, as it isn't useful. */ if (!op_is_flush(data->cmd_flags) && + !blk_op_is_passthrough(data->cmd_flags) && e->type->ops.limit_depth && !(data->flags & BLK_MQ_REQ_RESERVED)) e->type->ops.limit_depth(data->cmd_flags, data); -- cgit v1.2.3-59-g8ed1b