On Wed, 2011-02-02 at 12:51 +0200, Avi Kivity wrote: > On 02/02/2011 12:11 PM, Avi Kivity wrote: > > On 02/01/2011 05:57 PM, Glauber Costa wrote: > >> On Sun, 2011-01-30 at 16:04 +0200, Avi Kivity wrote: > >> > On 01/28/2011 09:52 PM, Glauber Costa wrote: > >> > > This patch accounts steal time time in kernel/sched. > >> > > I kept it from last proposal, because I still see advantages > >> > > in it: Doing it here will give us easier access from scheduler > >> > > variables such as the cpu rq. The next patch shows an example of > >> > > usage for it. > >> > > > >> > > Since functions like account_idle_time() can be called from > >> > > multiple places, not only account_process_tick(), steal time > >> > > grabbing is repeated in each account function separatedely. > >> > > > >> > > >> > I accept that steal time is worthwhile, but do you have some way to > >> > demonstrate that the implementation actually works and is beneficial? > >> > > >> > Perhaps run two cpu-bound compute processes on one vcpu, > >> overcommit that > >> > vcpu, and see what happens to the processing rate with and without > >> steal > >> > time accounting. I'd expect a fairer response with steal time > >> accounting. > >> > >> Avi, > >> > >> There are two things here: > >> One of them, which is solely the accounting of steal time, (patches 1 to > >> 4) has absolutely nothing to do with what you said. Its sole purpose is > >> to provide the user with information about "why is my process slow if I > >> am using 100 % of my cpu?") > > > > Right. Like irq and softirq time, we need to report this to the user, > > as it's potentially much higher. > > Of course, it's not enough to just account for this time, you also have > to expose it somewhere, and update tools like top(1) to display it. Yes, what I meant is that just the accounting will just expose it to the tools, won't affect the scheduler in any sense. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
