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

[Peter Zijlstra]

On Wed, Jul 12, 2023 at 11:04:16AM +0200, Geert Uytterhoeven wrote:
> Hoi Peter,
> 
> On Wed, Jul 12, 2023 at 10:05 AM Peter Zijlstra <peterz at infradead.org> wrote:
> > On Tue, Jul 11, 2023 at 11:39:17AM -1000, Tejun Heo wrote:
> > > I wonder whether the right thing to do here is somehow scaling the threshold
> > > according to the relative processing power. It's difficult to come up with a
> > > threshold which works well across the latest & fastest and really tiny CPUs.
> > > I'll think about it some more but if you have some ideas, please feel free
> > > to suggest.
> >
> > We could scale by BogoMIPS I suppose, it's a bogus measurement, as per
> > the name, but it does have some relation to how fast the machine is.
> 
> That's gonna fail miserably on e.g. ARM and RISC-V, where BogoMIPS
> depends on some timer frequency.
> 
> R-Car M2-W with 1.5 GHz Cortex-A15: 40.00 BogoMIPS
> R-Car V4H with 1.8 GHz Cortex-A76: 33.33 BogoMIPS
> 
> while the real slow 48 MHz VexRiscV gets 128 BogoMIPS.

Hehe, OK, really bogus then. Lets file this idea in the bit-bucket then.