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| author |   Lin Feng <linf@wangsu.com> | 2021-04-15 11:39:20 +0800 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2021-04-16 06:06:49 -0600 |
| commit | 8d663f34f8afcf5fc6a84c3cc4fa28cc84d58e39 (patch) | |
| tree | e2e2bfc66c32ed36a7a2f8f376f6e60da8909a75 /block | |
| parent | block: Remove an obsolete comment from sg_io() (diff) | |
| download | linux-dev-8d663f34f8afcf5fc6a84c3cc4fa28cc84d58e39.tar.xz linux-dev-8d663f34f8afcf5fc6a84c3cc4fa28cc84d58e39.zip | |
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.c | 3 |
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); |