On Monday 26 March 2007 15:11, Al Boldi wrote: > Con Kolivas wrote: > > Ok this one is heavily tested. Please try it when you find the time. > > It's better, but still skewed. Try two chew.c's; they account 80% each. > > > --- > > Currently we only do cpu accounting to userspace based on what is > > actually happening precisely on each tick. The accuracy of that > > accounting gets progressively worse the lower HZ is. As we already keep > > accounting of nanosecond resolution we can accurately track user cpu, > > nice cpu and idle cpu if we move the accounting to update_cpu_clock with > > a nanosecond cpu_usage_stat entry. > > That's great and much needed, but this is still probed; so what's wrong > with doing it in-lined? > > > This increases overhead slightly but > > avoids the problem of tick aliasing errors making accounting unreliable. > > Higher scheduling accuracy may actually offset any overhead incurred, so > it's well worth it; and if it's in-lined it should mean even less overhead. > > > + /* Sanity check. It should never go backwards or ruin accounting > > */ + if (unlikely(now < p->last_ran)) > > + goto out_set; > > If sched_clock() goes backwards, why not fix it, instead of hacking around > it? > > > Thanks!
Actually I'm going to give up this idea as not worth my effort given the sched_clock fsckage that seems to cause so much grief. If someone else wants to take up the challenge feel free to. Andrew please drop this patch. It's still broken and I have too much on my plate to try and debug it sorry. -- -ck - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
