Messages in this thread | | | Date | Mon, 8 Sep 2008 07:22:20 -0700 | From | Arjan van de Ven <> | Subject | Re: [PATCH 12/13] hrtimer: create a "timer_slack" field in the task struct |
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On Mon, 8 Sep 2008 16:15:55 +0200 Pavel Machek <pavel@suse.cz> wrote:
> On Mon 2008-09-08 06:40:02, Arjan van de Ven wrote: > > On Mon, 8 Sep 2008 15:27:16 +0200 > > Pavel Machek <pavel@suse.cz> wrote: > > > > > > > > ... which nobody uses today. > > > > It's not just new syscalls, it's a new glibc api as well at that > > > > point. > > > > > > ...and new applications, yes. I believe applications should > > > explicitely enable slacking timers. > > > > timers are slacking today, at least for select() and poll(), and > > are a great deal more so than the defaults in this patchkit. > > Ok, so select()/poll() may default to non-zero slack for legacy apps.
that's whats there > > > The great advantage of the prctl() approach (which is usable) over > > new system calls and glibc APIs is that it will get used, because > > the admin can use it just like he uses the "nice" command, on > > existing software. > > Yes, it is a great advantage, but it feels like a hack. Maybe it is > better done with LD_PRELOAD or something?
that's not working very well in general, and doesn't work across exec etc.
> > I'd certianly want the applications to specify slack themselves in > like 10 years.
We've been talking to Ulrich to figure out what the right API for this is (eg how to extend select/poll for this) and I still plan to work on this, but both Linus and Ulrich seem to be very ademant that it means only few apps will use it (and I agree with that, just look at how many apps use linux specific APIs such as sendfile(), linux AIO etc... )
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