Re: dynamic-hz

Nish Aravamudan
2004-12-14T16:59:42Z

On Tue, 14 Dec 2004 11:01:23 +0100, Domen Puncer <domen@coderock.org> wrote:
> On 13/12/04 19:54 -0800, Nish Aravamudan wrote:
> > On Mon, 13 Dec 2004 03:25:21 -0800, Andrew Morton <akpm@osdl.org> wrote:
> > > Andrea Arcangeli <andrea@suse.de> wrote:
> > > >
> > > > The patch only does HZ at dynamic time. But of course it's absolutely
> > > > trivial to define it at compile time, it's probably a 3 liner on top of
> > > > my current patch ;). However personally I don't think the three liner
> > > > will worth the few seconds more spent configuring the kernel ;).
> > >
> > > We still have 1000-odd places which do things like
> > >
> > > schedule_timeout(HZ/10);
> >
> ...
> > Many drivers use
> >
> > set_current_state(TASK_{UN,}INTERRUPTIBLE);
> > schedule_timeout(1); // or some other small value < 10
> >
> ...
> > If they really meant to use schedule_timeout(1) in the sense of
> > highest resolution delay possible (the latter above), then they
> > probably should just call schedule() directly.
>
> Um... no (and you should remember this from our discussions), schedule()
> gives up cpu until waitqueue wakeup or signal is received, and that can
> be a really long delay :-)

True; sorry about that, Domen, completely forgot about that. Will
think on it further.

-Nish