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authorLin Feng <linf@wangsu.com>2021-04-15 11:39:20 +0800
committerJens Axboe <axboe@kernel.dk>2021-04-16 06:06:49 -0600
commit8d663f34f8afcf5fc6a84c3cc4fa28cc84d58e39 (patch)
treee2e2bfc66c32ed36a7a2f8f376f6e60da8909a75 /block
parent347b546d5a9bd5871279a29be3dce8b5aad47ef6 (diff)
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 <linf@wangsu.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20210415033920.213963-1-linf@wangsu.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq.c3
1 files changed, 2 insertions, 1 deletions
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);

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