Re: [RFC] scsi: switch to scsi-mq by default

From: John Garry
Date: Wed Jul 04 2018 - 04:18:56 EST


On 04/07/2018 00:21, Bart Van Assche wrote:
On Tue, 2018-07-03 at 08:54 +0200, Johannes Thumshirn wrote:
It has been more than one year since we tried to change the default
from legacy to multi queue in SCSI. Back then we had to retract the
change because of performance issues with rotating disks.

In the meantime there have been a substantial amount of performance
improvements, thus we can re-enable scsi-mq without a significant
performance penalty.

Hello Johannes,

Please include references to commits cbe7dfa26eee ("Revert "scsi:
default to scsi-mq"") and 5c279bd9e406 ("scsi: default to scsi-mq").
I think it's a good idea to mention that suspend/resume now works
with scsi-mq.

Bart.

We were seeing performance drops previously for hisi_sas when originally enabled by default, but results on 4.18 seem almost identical with and without MQ default.

FWIW,

Acked-by: John Garry <john.garry@xxxxxxxxxx>