On 02/02/2021 20:48, Martin Wilck wrote:
On Tue, 2021-02-02 at 20:04 +0000, Don.Brace@xxxxxxxxxxxxx wrote:
-----Original Message-----
From: John Garry [mailto:john.garry@xxxxxxxxxx]
Subject: Re: [PATCH] scsi: scsi_host_queue_ready: increase busy count
early
Confirmed my suspicions - it looks like the host is sent more
commands than it can handle. We would need many disks to see this
issue though, which you have.
So for stable kernels, 6eb045e092ef is not in 5.4 . Next is 5.10, and
I suppose it could be simply fixed by setting .host_tagset in scsi
host template there.
Thanks,
John
--
Don: Even though this works for current kernels, what would chances
of this getting back-ported to 5.9 or even further?
Otherwise the original patch smartpqi_fix_host_qdepth_limit would
correct this issue for older kernels.
True. However this is 5.12 material, so we shouldn't be bothered by
that here. For 5.5 up to 5.9, you need a workaround. But I'm unsure
whether smartpqi_fix_host_qdepth_limit would be the solution.
You could simply divide can_queue by nr_hw_queues, as suggested before,
or even simpler, set nr_hw_queues = 1.
How much performance would that cost you?
Distribution kernels would be yet another issue, distros can backport
host_tagset and get rid of the issue.
Aren't they (distros) the only issue? As I mentioned above, for 5.10
mainline stable, I think it's reasonable to backport a patch to set
.host_tagset for the driver.
Thanks,
John
