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| author | John Garry <john.garry@huawei.com> | 2021-10-05 13:23:37 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-10-18 15:17:03 +0300 |
| commit | e155b0c238b20f0a866f4334d292656665836c8a (patch) | |
| tree | b15573dfa9eb29747802e2ba407d1e0381ca66d8 /include/linux/blk-mq.h | |
| parent | 645db34e50501aac141713fb47a315e5202ff890 (diff) | |
| download | linux-e155b0c238b20f0a866f4334d292656665836c8a.tar.xz | |
blk-mq: Use shared tags for shared sbitmap support
Currently we use separate sbitmap pairs and active_queues atomic_t for
shared sbitmap support.
However a full sets of static requests are used per HW queue, which is
quite wasteful, considering that the total number of requests usable at
any given time across all HW queues is limited by the shared sbitmap depth.
As such, it is considerably more memory efficient in the case of shared
sbitmap to allocate a set of static rqs per tag set or request queue, and
not per HW queue.
So replace the sbitmap pairs and active_queues atomic_t with a shared
tags per tagset and request queue, which will hold a set of shared static
rqs.
Since there is now no valid HW queue index to be passed to the blk_mq_ops
.init and .exit_request callbacks, pass an invalid index token. This
changes the semantics of the APIs, such that the callback would need to
validate the HW queue index before using it. Currently no user of shared
sbitmap actually uses the HW queue index (as would be expected).
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/1633429419-228500-13-git-send-email-john.garry@huawei.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 | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 31cc41dfef6b..faa20a19bfcc 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -440,13 +440,11 @@ enum hctx_type { * @flags: Zero or more BLK_MQ_F_* flags. * @driver_data: Pointer to data owned by the block driver that created this * tag set. - * @active_queues_shared_sbitmap: - * number of active request queues per tag set. - * @__bitmap_tags: A shared tags sbitmap, used over all hctx's - * @__breserved_tags: - * A shared reserved tags sbitmap, used over all hctx's * @tags: Tag sets. One tag set per hardware queue. Has @nr_hw_queues * elements. + * @shared_sbitmap_tags: + * Shared sbitmap set of tags. Has @nr_hw_queues elements. If + * set, shared by all @tags. * @tag_list_lock: Serializes tag_list accesses. * @tag_list: List of the request queues that use this tag set. See also * request_queue.tag_set_list. @@ -463,12 +461,11 @@ struct blk_mq_tag_set { unsigned int timeout; unsigned int flags; void *driver_data; - atomic_t active_queues_shared_sbitmap; - struct sbitmap_queue __bitmap_tags; - struct sbitmap_queue __breserved_tags; struct blk_mq_tags **tags; + struct blk_mq_tags *shared_sbitmap_tags; + struct mutex tag_list_lock; struct list_head tag_list; }; @@ -640,6 +637,8 @@ enum { ((policy & ((1 << BLK_MQ_F_ALLOC_POLICY_BITS) - 1)) \ << BLK_MQ_F_ALLOC_POLICY_START_BIT) +#define BLK_MQ_NO_HCTX_IDX (-1U) + struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set, void *queuedata, struct lock_class_key *lkclass); #define blk_mq_alloc_disk(set, queuedata) \ |