Skip to content

K
Kernel

openeuler / Kernel
接近 2 年 前同步成功

通知 8
Star 0
Fork 0
K
Kernel
切换分支/标签
  1. 18 10月, 2021 8 次提交
  3. 16 10月, 2021 1 次提交
  5. 08 9月, 2021 1 次提交
  7. 24 8月, 2021 4 次提交
  9. 18 8月, 2021 1 次提交
    • M
      blk-mq: fix is_flush_rq · a9ed27a7
      由 Ming Lei 提交于 
      is_flush_rq() is called from bt_iter()/bt_tags_iter(), and runs the
following check:

	hctx->fq->flush_rq == req

but the passed hctx from bt_iter()/bt_tags_iter() may be NULL because:

1) memory re-order in blk_mq_rq_ctx_init():

	rq->mq_hctx = data->hctx;
	...
	refcount_set(&rq->ref, 1);

OR

2) tag re-use and ->rqs[] isn't updated with new request.

Fix the issue by re-writing is_flush_rq() as:

	return rq->end_io == flush_end_io;

which turns out simpler to follow and immune to data race since we have
ordered WRITE rq->end_io and refcount_set(&rq->ref, 1).

Fixes: 2e315dc0 ("blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter")
Cc: "Blank-Burian, Markus, Dr." <blankburian@uni-muenster.de>
Cc: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210818010925.607383-1-ming.lei@redhat.comSigned-off-by: NJens Axboe <axboe@kernel.dk>
      a9ed27a7
  11. 17 8月, 2021 1 次提交
  13. 13 8月, 2021 1 次提交
  15. 11 8月, 2021 1 次提交
  17. 10 8月, 2021 1 次提交
  19. 31 7月, 2021 1 次提交
  21. 01 7月, 2021 1 次提交
  23. 25 6月, 2021 1 次提交
  25. 18 6月, 2021 3 次提交
  27. 12 6月, 2021 4 次提交
  29. 04 6月, 2021 1 次提交
    • J
      block: Do not pull requests from the scheduler when we cannot dispatch them · 61347154
      由 Jan Kara 提交于 
      Provided the device driver does not implement dispatch budget accounting
(which only SCSI does) the loop in __blk_mq_do_dispatch_sched() pulls
requests from the IO scheduler as long as it is willing to give out any.
That defeats scheduling heuristics inside the scheduler by creating
false impression that the device can take more IO when it in fact
cannot.

For example with BFQ IO scheduler on top of virtio-blk device setting
blkio cgroup weight has barely any impact on observed throughput of
async IO because __blk_mq_do_dispatch_sched() always sucks out all the
IO queued in BFQ. BFQ first submits IO from higher weight cgroups but
when that is all dispatched, it will give out IO of lower weight cgroups
as well. And then we have to wait for all this IO to be dispatched to
the disk (which means lot of it actually has to complete) before the
IO scheduler is queried again for dispatching more requests. This
completely destroys any service differentiation.

So grab request tag for a request pulled out of the IO scheduler already
in __blk_mq_do_dispatch_sched() and do not pull any more requests if we
cannot get it because we are unlikely to be able to dispatch it. That
way only single request is going to wait in the dispatch list for some
tag to free.
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210603104721.6309-1-jack@suse.czSigned-off-by: NJens Axboe <axboe@kernel.dk>
      61347154
  31. 24 5月, 2021 5 次提交
  33. 14 5月, 2021 2 次提交
  35. 16 4月, 2021 1 次提交
    • L
      blk-mq: bypass IO scheduler's limit_depth for passthrough request · 8d663f34
      由 Lin Feng 提交于 
      Commit 01e99aec ("blk-mq: insert passthrough request into
hctx->dispatch directly") gives high priority to passthrough requests and
bypass underlying IO scheduler. But as we allocate tag for such request it
still runs io-scheduler's callback limit_depth, while we really want is to
give full sbitmap-depth capabity to such request for acquiring available
tag.
blktrace shows PC requests(dmraid -s -c -i) hit bfq's limit_depth:
  8,0    2        0     0.000000000 39952 1,0  m   N bfq [bfq_limit_depth] wr_busy 0 sync 0 depth 8
  8,0    2        1     0.000008134 39952  D   R 4 [dmraid]
  8,0    2        2     0.000021538    24  C   R [0]
  8,0    2        0     0.000035442 39952 1,0  m   N bfq [bfq_limit_depth] wr_busy 0 sync 0 depth 8
  8,0    2        3     0.000038813 39952  D   R 24 [dmraid]
  8,0    2        4     0.000044356    24  C   R [0]

This patch introduce a new wrapper to make code not that ugly.
Signed-off-by: NLin Feng <linf@wangsu.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210415033920.213963-1-linf@wangsu.comSigned-off-by: NJens Axboe <axboe@kernel.dk>
      8d663f34
  37. 09 4月, 2021 1 次提交
  39. 05 3月, 2021 1 次提交