Re: [RFC] sleepy linux

Ingo Molnar
2008-01-08T16:37:44Z

* Pavel Machek <pavel@ucw.cz> wrote:

> > a quick feature request: could you please make the wake-on-RTC
> > capability generic and add a CONFIG_DEBUG_SUSPEND_ON_RAM=y config
> > option (disabled by default) that does a short 1-second
> > suspend-to-RAM sequence upon bootup? That way we could test s2ram
> > automatically (which is a MUCH needed feature for automated
> > regression testing and automatic bisection). In addition, some sort
> > of 'suspend for N seconds' /sys or /dev/rtc capability would be nice
> > as well.
>
> Hmm, are you sure it is good idea to do this from kernel? I guess this
> is better done from script...

i have this low-prio effort to make all self-checks automatically
available via 'make randconfig' as well, for all features that have no
natural exposure during normal bootup. So far we've got rcutorture,
kprobes-check, locking/lockdep-self-test and a handful of others.
External scripts tend to go out of sync and LTP takes way too much time
to finish.

> > btw., how far are you from having a working prototype?
>
> SCSI/SATA issues stop me just now, but even if I get that to work, it
> will be extremely disgusting hack... and it is unclear how to do it
> nicely :-(.

as long as the sleep periods are within say 10-20 seconds, and our s2ram
cycle is fast and optimal enough, we could do this with networking
enabled too, without dropping/stalling TCP connections left and right.

(Perhaps if we could notify routers that they should batch packets for N
seconds and we could turn off PHY during that time, it would be even
nicer - is there any such router extension in existence?)

but if it's nothing else but a s2ram debug/stress utility, that alone
would be great too :-)

Ingo