Re: [patch] hrtimer: round up relative start time on low-res arches

From: john stultz
Date: Wed Feb 15 2006 - 14:28:36 EST


On Wed, 2006-02-15 at 13:26 +0100, Roman Zippel wrote:
> Hi,
>
> On Wed, 15 Feb 2006, Ingo Molnar wrote:
>
> > yeah, agreed. That will be accurately fixed via GTOD's per-hwclock
> > resolution values. It will have another advantage as well: e.g. the
> > whole of m68k wont be penalized via CONFIG_TIME_LOW_RES for having a
> > handful of sub-arches (Apollo, Sun3x, Q40) that dont have a higher
> > resolution timer - every clock can define its own resolution. You could
> > help that effort by porting m68k to use GTOD ;-)
>
> I'll do that as soon as the perfomance is equal or better than what we
> have right now and expensive 64bit math in the fast path, where it's
> provably a waste, is not exactly encouraging. I already provided all the
> math and code to keep it cheap and (relatively) simple, but I don't have
> the time to work constantly on it, so if you'd help to integrate it into
> John's work it would go a lot faster.

Hey Roman,
I just wanted to make sure you know I'm not ignoring your suggestions.
I do appreciate the time you have spent, and I have been continuing to
work on implementing your idea. Unfortunately the code is not trivial
and very much hurts the readability. I expect thats a sacrifice that
will be necessary, but hopefully after some review cycles we'll be able
to come to something we both like.

I'm hoping to have a first pass patch I can mail this week.

thanks
-john

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