| Message ID | 1628519378-211232-1-git-send-email-john.garry@huawei.com |
|---|---|
| Headers | show |
| Series | blk-mq: Reduce static requests memory footprint for shared sbitmap | expand |
On 09/08/2021 15:29, John Garry wrote: Hi guys, Any chance to review or test this? Thanks! > Currently a full set of static requests are allocated per hw queue per > tagset when shared sbitmap is used. > > However, only tagset->queue_depth number of requests may be active at > any given time. As such, only tagset->queue_depth number of static > requests are required. > > The same goes for using an IO scheduler, which allocates a full set of > static requests per hw queue per request queue. > > This series changes shared sbitmap support by using a shared tags per > tagset and request queue. Ming suggested something along those lines in > v1. But we'll keep name "shared sbitmap" name as it is fimilar. In using > a shared tags, the static rqs also become shared, reducing the number of > sets of static rqs, reducing memory usage. > > Patch "blk-mq: Use shared tags for shared sbitmap support" is a bit big, > and could be broken down. But then maintaining ability to bisect > becomes harder and each sub-patch would get more convoluted. > > For megaraid sas driver on my 128-CPU arm64 system with 1x SATA disk, we > save approx. 300MB(!) [370MB -> 60MB] > > Baseline is 2112f5c1330a (for-5.15/block) loop: Select I/O scheduler ... > > Changes since v1: > - Switch to use blk_mq_tags for shared sbitmap > - Add new blk_mq_ops init request callback > - Add some RB tags (thanks!) > > John Garry (11): > blk-mq: Change rqs check in blk_mq_free_rqs() > block: Rename BLKDEV_MAX_RQ -> BLKDEV_DEFAULT_RQ > blk-mq: Relocate shared sbitmap resize in blk_mq_update_nr_requests() > blk-mq: Invert check in blk_mq_update_nr_requests() > blk-mq-sched: Rename blk_mq_sched_alloc_{tags -> map_and_request}() > blk-mq: Pass driver tags to blk_mq_clear_rq_mapping() > blk-mq: Add blk_mq_tag_update_sched_shared_sbitmap() > blk-mq: Add blk_mq_ops.init_request_no_hctx() > scsi: Set blk_mq_ops.init_request_no_hctx > blk-mq: Use shared tags for shared sbitmap support > blk-mq: Stop using pointers for blk_mq_tags bitmap tags > > block/bfq-iosched.c | 4 +- > block/blk-core.c | 2 +- > block/blk-mq-debugfs.c | 8 +-- > block/blk-mq-sched.c | 92 +++++++++++++------------ > block/blk-mq-sched.h | 2 +- > block/blk-mq-tag.c | 111 +++++++++++++----------------- > block/blk-mq-tag.h | 12 ++-- > block/blk-mq.c | 144 +++++++++++++++++++++++---------------- > block/blk-mq.h | 8 +-- > block/kyber-iosched.c | 4 +- > block/mq-deadline-main.c | 2 +- > drivers/block/rbd.c | 2 +- > drivers/scsi/scsi_lib.c | 6 +- > include/linux/blk-mq.h | 20 +++--- > include/linux/blkdev.h | 5 +- > 15 files changed, 218 insertions(+), 204 deletions(-) >
Currently a full set of static requests are allocated per hw queue per tagset when shared sbitmap is used. However, only tagset->queue_depth number of requests may be active at any given time. As such, only tagset->queue_depth number of static requests are required. The same goes for using an IO scheduler, which allocates a full set of static requests per hw queue per request queue. This series changes shared sbitmap support by using a shared tags per tagset and request queue. Ming suggested something along those lines in v1. But we'll keep name "shared sbitmap" name as it is fimilar. In using a shared tags, the static rqs also become shared, reducing the number of sets of static rqs, reducing memory usage. Patch "blk-mq: Use shared tags for shared sbitmap support" is a bit big, and could be broken down. But then maintaining ability to bisect becomes harder and each sub-patch would get more convoluted. For megaraid sas driver on my 128-CPU arm64 system with 1x SATA disk, we save approx. 300MB(!) [370MB -> 60MB] Baseline is 2112f5c1330a (for-5.15/block) loop: Select I/O scheduler ... Changes since v1: - Switch to use blk_mq_tags for shared sbitmap - Add new blk_mq_ops init request callback - Add some RB tags (thanks!) John Garry (11): blk-mq: Change rqs check in blk_mq_free_rqs() block: Rename BLKDEV_MAX_RQ -> BLKDEV_DEFAULT_RQ blk-mq: Relocate shared sbitmap resize in blk_mq_update_nr_requests() blk-mq: Invert check in blk_mq_update_nr_requests() blk-mq-sched: Rename blk_mq_sched_alloc_{tags -> map_and_request}() blk-mq: Pass driver tags to blk_mq_clear_rq_mapping() blk-mq: Add blk_mq_tag_update_sched_shared_sbitmap() blk-mq: Add blk_mq_ops.init_request_no_hctx() scsi: Set blk_mq_ops.init_request_no_hctx blk-mq: Use shared tags for shared sbitmap support blk-mq: Stop using pointers for blk_mq_tags bitmap tags block/bfq-iosched.c | 4 +- block/blk-core.c | 2 +- block/blk-mq-debugfs.c | 8 +-- block/blk-mq-sched.c | 92 +++++++++++++------------ block/blk-mq-sched.h | 2 +- block/blk-mq-tag.c | 111 +++++++++++++----------------- block/blk-mq-tag.h | 12 ++-- block/blk-mq.c | 144 +++++++++++++++++++++++---------------- block/blk-mq.h | 8 +-- block/kyber-iosched.c | 4 +- block/mq-deadline-main.c | 2 +- drivers/block/rbd.c | 2 +- drivers/scsi/scsi_lib.c | 6 +- include/linux/blk-mq.h | 20 +++--- include/linux/blkdev.h | 5 +- 15 files changed, 218 insertions(+), 204 deletions(-) -- 2.26.2