On Wed 03-02-21 16:18:59, John Garry wrote: > 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 ... I also don't consider my series a stable tree material. The setup of multiple HW queues with BFQ IO scheduler isn't really very common... Honza > > 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. > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
