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* [PATCH 0/2 RFC] blk-mq: Improve performance of non-mq IO schedulers with multiple HW queues
@ 2020-12-18 21:44 Jan Kara
  2020-12-18 21:44 ` [PATCH 1/2] Revert "blk-mq, elevator: Count requests per hctx to improve performance" Jan Kara
  2020-12-18 21:44 ` [PATCH 2/2] blk-mq: Improve performance of non-mq IO schedulers with multiple HW queues Jan Kara
  0 siblings, 2 replies; 14+ messages in thread
From: Jan Kara @ 2020-12-18 21:44 UTC (permalink / raw)
  To: Jens Axboe; +Cc: linux-block, hare, Kashyap Desai, Jan Kara

Hello!

This patch series aims to fix a regression we've noticed on our test grid when
support for multiple HW queues in megaraid_sas driver was added during the 5.10
cycle (103fbf8e4020 scsi: megaraid_sas: Added support for shared host tagset
for cpuhotplug). The commit was reverted in the end for other reasons but I
believe the fundamental problem still exists for any other similar setup. The
problem manifests when the storage card supports multiple hardware queues
however storage behind it is slow (single rotating disk in our case) and so
using IO scheduler such as BFQ is desirable. See the second patch for details.

FWIW I'm not 100% sold on this approach, in particular I'm not sure it cannot
cause some issues in higher-end setups but I want expect mq-deadline or BFQ
to be used there. Anyway that's why I'm sending this as an RFC.

								Honza

^ permalink raw reply	[flat|nested] 14+ messages in thread
* [PATCH 0/2 v2] blk-mq: Improve performance of non-mq IO schedulers with multiple HW queues
@ 2021-01-06 10:24 Jan Kara
  2021-01-06 10:24 ` [PATCH 2/2] " Jan Kara
  0 siblings, 1 reply; 14+ messages in thread
From: Jan Kara @ 2021-01-06 10:24 UTC (permalink / raw)
  To: Jens Axboe; +Cc: linux-block, Ming Lei, Jan Kara

Hello!

This patch series aims to fix a regression we've noticed on our test grid when
support for multiple HW queues in megaraid_sas driver was added during the 5.10
cycle (103fbf8e4020 scsi: megaraid_sas: Added support for shared host tagset
for cpuhotplug). The commit was reverted in the end for other reasons but I
believe the fundamental problem still exists for any other similar setup. The
problem manifests when the storage card supports multiple hardware queues
however storage behind it is slow (single rotating disk in our case) and so
using IO scheduler such as BFQ is desirable. See the second patch for details.

								Honza

^ permalink raw reply	[flat|nested] 14+ messages in thread
* [PATCH 0/2 v3] blk-mq: Improve performance of non-mq IO schedulers with multiple HW queues
@ 2021-01-11 16:47 Jan Kara
  2021-01-11 16:47 ` [PATCH 2/2] " Jan Kara
  0 siblings, 1 reply; 14+ messages in thread
From: Jan Kara @ 2021-01-11 16:47 UTC (permalink / raw)
  To: Jens Axboe; +Cc: linux-block, Ming Lei, Jan Kara

Hello!

This patch series aims to fix a regression we've noticed on our test grid when
support for multiple HW queues in megaraid_sas driver was added during the 5.10
cycle (103fbf8e4020 scsi: megaraid_sas: Added support for shared host tagset
for cpuhotplug). The commit was reverted in the end for other reasons but I
believe the fundamental problem still exists for any other similar setup. The
problem manifests when the storage card supports multiple hardware queues
however storage behind it is slow (single rotating disk in our case) and so
using IO scheduler such as BFQ is desirable. See the second patch for details.

Changes since v2
* Modified code to avoid useless sbitmap_any_set() calls on submit path

Changes since v1
* Fixed queue running code to don't leave pending requests that bypass IO
  scheduler.


								Honza

^ permalink raw reply	[flat|nested] 14+ messages in thread

end of thread, other threads:[~2021-01-12  2:17 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-12-18 21:44 [PATCH 0/2 RFC] blk-mq: Improve performance of non-mq IO schedulers with multiple HW queues Jan Kara
2020-12-18 21:44 ` [PATCH 1/2] Revert "blk-mq, elevator: Count requests per hctx to improve performance" Jan Kara
2020-12-18 21:44 ` [PATCH 2/2] blk-mq: Improve performance of non-mq IO schedulers with multiple HW queues Jan Kara
2020-12-19  3:14   ` Ming Lei
2020-12-22 10:18     ` Jan Kara
2020-12-22 16:55       ` Jan Kara
2020-12-23  3:43         ` Ming Lei
2020-12-23  3:33       ` Ming Lei
2021-01-06 10:24 [PATCH 0/2 v2] " Jan Kara
2021-01-06 10:24 ` [PATCH 2/2] " Jan Kara
2021-01-07  6:19   ` Ming Lei
2021-01-07 11:18     ` Jan Kara
2021-01-07 12:06       ` Ming Lei
2021-01-11 16:47 [PATCH 0/2 v3] " Jan Kara
2021-01-11 16:47 ` [PATCH 2/2] " Jan Kara
2021-01-12  2:15   ` Ming Lei

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