mirros/rockchip-kernel
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

blk-mq: Use shared tags for shared sbitmap support

Browse Source 
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>
This commit is contained in:
John Garry
2021-10-05 18:23:37 +08:00
committed by Jens Axboe
parent 645db34e50
commit e155b0c238
7 changed files with 126 additions and 153 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/blkdev.h
View File

@@ -238,8 +238,7 @@ struct request_queue {
atomic_t nr_active_requests_shared_sbitmap;
struct sbitmap_queue sched_bitmap_tags;
struct sbitmap_queue sched_breserved_tags;
struct blk_mq_tags *shared_sbitmap_tags;
struct list_head icq_list;
#ifdef CONFIG_BLK_CGROUP