Re: [PATCH] stopmachine: add stopmachine_timeout

[Max Krasnyansky]

Rusty Russell wrote:
> On Tuesday 15 July 2008 12:24:54 Max Krasnyansky wrote:
> > Heiko Carstens wrote:
> > > On Mon, Jul 14, 2008 at 11:56:18AM -0700, Jeremy Fitzhardinge wrote:
> > > This is asking for trouble... a config option to disable this would be
> > > nice. But as I don't know which problem this patch originally addresses
> > > it might be that this is needed anyway. So lets see why we need it first.
> > How about this. We'll make this a sysctl, as Rusty already did, and set the
> > default to 0 which means "never timeout". That way crazy people like me who
> > care about this scenario can enable this feature.
>
> Indeed, this was my thought too.  s390 can initialize it to zero somewhere in 
> their boot code.
>
> > btw Rusty, I just had this "why didn't I think of that" moments. This is
> > actually another way of handling my workload. I mean it certainly does not
> > fix the root case of the problems and we still need other things that we
> > talked about (non-blocking module delete, lock-free module insertion, etc)
> > but at least in the mean time it avoids wedging the machines for good.
> > btw I'd like that timeout in milliseconds. I think 5 seconds is way tooooo
> > long :).
>
> We can make it ms, sure.  200ms should be plenty of time: worst I ever saw was 
> 150ms, and that was some weird Power box doing crazy stuff.  I wouldn't be 
> surprised if you'd never see 1ms on your hardware.
Sounds good.

> The ipi idea would handle your case a little more nicely, too, but that's 
> probably not going to hit this merge window.
Which reminds me that I wanted to submit a bunch of kthread and workqueue
related things in this window :).

Max
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