On Mon, 2011-01-31 at 00:45 +0800, lidong chen wrote: > I think we can use performance counter. > use unhalted core cycles event, in the nmi callback funcation, count > which process is running . > if the vm exit is caused by nmi,discard it. > the system time of qemu process is the time steal by kvm. Performance counters are a scarce resource, so I'd rather not use them, since it will mean forcing a context switch from whoever is using it at the moment. Which is also an expensive operation anyway. So even though it can be possible, in theory, I don't see why use it in this particular case. > > > 2011/1/30 Avi Kivity <avi@xxxxxxxxxx>: > > 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. > > > > -- > > error compiling committee.c: too many arguments to function > > > > -- > > 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 > > -- 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
