On 2022-08-17 20:15, Jan Kara wrote:

On Wed 17-08-22 13:57:00, Chris Murphy wrote:

quoted

On Wed, Aug 17, 2022, at 12:47 PM, Chris Murphy wrote:
Can you boot with

quoted

quoted

"megaraid_sas.host_tagset_enable = 0" kernel option and see whether the
issue reproduces?

This has been running an hour without symptoms. It's strongly suggestive,
but needs to run overnight to be sure. Anecdotally, the max write IO is
less than what I'm used to seeing.

OK, if this indeed passes then b6e68ee82585 ("blk-mq: Improve performance
of non-mq IO schedulers with multiple HW queues") might be what's causing
issues (although I don't know how yet...).

								Honza

Certainly explains why BFQ turned up as a suspect, considering it's still
single-queue (fair MQ scheduling is .. complicated).

-h