On Mon, 2007-03-26 at 08:11 +0300, Al Boldi wrote: > > + /* 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?
When tasks change cpu, timestamp correction is attempted, but isn't perfect (perfection: submit patch to read remote clock - people likely toast poor submitter's buns very thoroughly). Timewarps happen, and even on Intel processors there seems to be very small difference in TSCs in the same package. (that's what instrumentation here said must be true, possible booboos aside) -Mike - 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/