| From: |
| Ming Lei <ming.lei-AT-redhat.com> |
| To: |
| Jens Axboe <axboe-AT-kernel.dk>, linux-block-AT-vger.kernel.org |
| Subject: |
| [PATCH 0/5] blk-mq: Replace tags->lock with SRCU for tag iterators |
| Date: |
| Fri, 01 Aug 2025 19:44:32 +0800 |
| Message-ID: |
| <20250801114440.722286-1-ming.lei@redhat.com> |
| Cc: |
| Yu Kuai <yukuai3-AT-huawei.com>, John Garry <john.garry-AT-huawei.com>, Sathya Prakash Veerichetty <sathya.prakash-AT-broadcom.com>, Ming Lei <ming.lei-AT-redhat.com> |
| Archive-link: |
| Article |
Hello Jens,
Replace the spinlock in blk_mq_find_and_get_req() with an SRCU read lock
around the tag iterators.
Avoids scsi_host_busy() lockup during scsi host blocked in case of big cpu
cores & deep queue depth.
Also it becomes possible to use blk_mq_in_driver_rw() for io accounting now.
Take the following approach:
- clearing rq reference in tags->rqs[] and deferring freeing scheduler requests
in SRCU callback
- replace tags->lock with srcu read lock in tags iterator.
Ming Lei (5):
blk-mq: Move flush queue allocation into blk_mq_init_hctx()
blk-mq: Pass tag_set to blk_mq_free_rq_map/tags
blk-mq: Defer freeing of tags page_list to SRCU callback
blk-mq: Defer freeing flush queue to SRCU callback
blk-mq: Replace tags->lock with SRCU for tag iterators
block/blk-mq-sched.c | 4 +-
block/blk-mq-sysfs.c | 1 -
block/blk-mq-tag.c | 38 +++++++++++++++---
block/blk-mq.c | 87 +++++++++++++++++++++---------------------
block/blk-mq.h | 4 +-
block/blk.h | 1 +
include/linux/blk-mq.h | 2 +
7 files changed, 82 insertions(+), 55 deletions(-)
--
2.47.0
