On Tue, 2007-08-21 at 09:00 +0200, Christian Borntraeger wrote: > Am Montag, 20. August 2007 schrieb Martin Schwidefsky: > > On Mon, 2007-08-20 at 20:08 +0200, Ingo Molnar wrote: > > Ok, that would mean that sched_clock can just return the virtual cpu > > time and the two hooks starts and stops the idle periods as far as the > > scheduler is concerned. In this case we can use the patch from Jan with > > the new implementation for sched_clock and add the two hooks to the > > places where the cpu-idle notifiers are done (do_monitor_call and > > default_idle). In fact this could be an idle-notifier. Hmm, I take a > > closer look tomorrow when I'm back at the office. > > > > > If a virtual CPU is idle then i think the "real = steal, virtual = 0" > > > way of thinking about idle looks a bit unnatural to me - wouldnt it be > > > better to think in terms of "steal = 0, virtual = real" ? Basically a > > > virtual CPU can idle at "perfect speed", without the host "stealing" any > > > cycles from it. And with that way of thinking, if s390 passed in the > > > real-idle-time value to the new callbacks below it would all fall into > > > place. Hm? > > Martin, > > I think we already do something like this. If you look at cpustat in 2.6.22 > and earlier we already have steal increase = 0, idle increase = 100 % on an > idle cpu, even on s390. So while from the hardware perspective steal is > growing, we do the right thing in Linux, no?
This is done in kernel/sched.c:account_steal_time(). If the architecture backend reports steal time for idle it is accounted as idle time. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. - 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/
