On Thu, Aug 02, 2007 at 08:57:47PM -0700, Arjan van de Ven wrote: > On Thu, 2007-08-02 at 22:04 -0500, Matt Mackall wrote: > > On Wed, Aug 01, 2007 at 01:22:29PM +0200, Ingo Molnar wrote: > > > > > > * Roman Zippel <[EMAIL PROTECTED]> wrote: > > > > > > > [...] e.g. in this example there are three tasks that run only for > > > > about 1ms every 3ms, but they get far more time than should have > > > > gotten fairly: > > > > > > > > 4544 roman 20 0 1796 520 432 S 32.1 0.4 0:21.08 lt > > > > 4545 roman 20 0 1796 344 256 R 32.1 0.3 0:21.07 lt > > > > 4546 roman 20 0 1796 344 256 R 31.7 0.3 0:21.07 lt > > > > 4547 roman 20 0 1532 272 216 R 3.3 0.2 0:01.94 l > > > > > > Mike and me have managed to reproduce similarly looking 'top' output, > > > but it takes some effort: we had to deliberately run a non-TSC > > > sched_clock(), CONFIG_HZ=100, !CONFIG_NO_HZ and !CONFIG_HIGH_RES_TIMERS. > > > > ..which is pretty much the state of play for lots of non-x86 hardware. > > question is if it's significantly worse than before. With a 100 or > 1000Hz timer, you can't expect perfect fairness just due to the > extremely rough measurement of time spent...
Indeed. I'm just pointing out that not having TSC, fast HZ, no-HZ mode, or high-res timers should not be treated as an unusual circumstance. That's a PC-centric view. -- Mathematics is the supreme nostalgia of our time. - 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/
