Re: [RFC][PATCH] PM / Hibernate: Add sysfs knob to control size of memory for drivers
From: Rafael J. Wysocki
Date: Wed May 18 2011 - 16:23:22 EST
On Wednesday, May 18, 2011, Pavel Machek wrote:
> > > > OK, there are no comments, so my understanding is that everyone is
> > > > fine with this patch and I can add it to my linux-next branch.
> > >
> > > Actually no, I don't like it. Yes, knob might be useful for debugging,
> > > but having it as part of official kernel interface...
> > Well I and people with similar setups it is actually quite useful. It
> > makes the difference between does hibernate *every time* versus does not
> > hibernate sometimes. And I don't see why it can't go again, when the issue
> > is taken care of elsewise in the future. I think that autotuning / drivers
> > allocating their memory via whatnot is better, but until such a mechanism
> > is agreed, developed and included in official kernel I do think that this
> > knob does help.
> Yes, autotuning would be better, and yes, knob is useful for you now.
> I'd say the knob is for debugging and should go to debugfs somewhere.
> > I think missing is some documentation so that the advanced user can figure
> > out this knob.
> ...so we can easily delete the knob when it is no longer neccessary.
_If_ drivers start to allocate memory in .prepare(), the knob won't be
necessary any more and _then_ we may consider removing it. I guess a lot
of time will pass before that happens, though. :-)
That said, I'm not sure we should recommend using it beyond the cases in which
nothing else works.
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