Re: Consider switching to WQ_UNBOUND messages (was: Re: [PATCH v2 6/7] workqueue: Report work funcs that trigger automatic CPU_INTENSIVE mechanism)

[Tejun Heo]

Hello,

On Tue, Jul 18, 2023 at 11:54:58AM +0200, Geert Uytterhoeven wrote:
> I gave it a try on a system with an 800 MHz Cortex A9, only to discover
> it makes no difference, as that machine has 1600 BogoMIPS:

Oops.

> workqueue: blk_mq_run_work_fn hogged CPU for >10000us 4 times,
> consider switching to WQ_UNBOUND

It could be that we actually want to switch to UNBOUND for some reports but
the above triggering most likely indicates that the threshold is too
aggressive.

> Artificially low BogoMIPS numbers only happen on systems that have
> the related timers (Cortex A7/A15 and later, Cortex A9 MPCore,
> and arm64).

Ah, I see. Thanks for the explanation.

> I will test on more systems, but that will probably not happen until
> next week...

Thanks, really appreciate it. Can you try the following instead when you
have time? I just pushed up the lower boundary to 4000 MIPS. The scaling is
still capped at 1s.