diff options
| author | Ming Lei <ming.lei@redhat.com> | 2021-12-03 16:15:32 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-12-04 00:51:29 +0300 |
| commit | 704b914f15fb7daaf517e3acc4bed472b50ca19e (patch) | |
| tree | 5fffc1140fef4ddceeaae58e44fbb65333c33861 /include/linux/blk-mq.h | |
| parent | 2a904d00855f94cb85751e45fa494f225d44ae0d (diff) | |
| download | linux-704b914f15fb7daaf517e3acc4bed472b50ca19e.tar.xz | |
blk-mq: move srcu from blk_mq_hw_ctx to request_queue
In case of BLK_MQ_F_BLOCKING, per-hctx srcu is used to protect dispatch
critical area. However, this srcu instance stays at the end of hctx, and
it often takes standalone cacheline, often cold.
Inside srcu_read_lock() and srcu_read_unlock(), WRITE is always done on
the indirect percpu variable which is allocated from heap instead of
being embedded, srcu->srcu_idx is read only in srcu_read_lock(). It
doesn't matter if srcu structure stays in hctx or request queue.
So switch to per-request-queue srcu for protecting dispatch, and this
way simplifies quiesce a lot, not mention quiesce is always done on the
request queue wide.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20211203131534.3668411-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/blk-mq.h')
| -rw-r--r-- | include/linux/blk-mq.h | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 561beb5be7ec..ecdc049b52fa 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -4,7 +4,6 @@ #include <linux/blkdev.h> #include <linux/sbitmap.h> -#include <linux/srcu.h> #include <linux/lockdep.h> #include <linux/scatterlist.h> #include <linux/prefetch.h> @@ -375,13 +374,6 @@ struct blk_mq_hw_ctx { * q->unused_hctx_list. */ struct list_head hctx_list; - - /** - * @srcu: Sleepable RCU. Use as lock when type of the hardware queue is - * blocking (BLK_MQ_F_BLOCKING). Must be the last member - see also - * blk_mq_hw_ctx_size(). - */ - struct srcu_struct srcu[]; }; /** |