On 25/01/2021 01:20, Jens Axboe wrote:
On 1/11/21 9:47 AM, Jan Kara wrote:
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.
That commit made it into 5.11-rc, and other SCSI HBA expose HW queues in
5.10 and earlier. But then this series is targeted at 5.12.
Question: can we consider backport this series just due to performance
issue regression? I'd say no, but maybe someone strongly disagrees with
me ...
Thanks,
John
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.
