Re: [Coremu-list-devel] How do you measure timing on COREMU?

[zhaoguo w. <tig...@gm...>]

The time is not accurate is because we change the timer interrupt emulation
mechanism when #emulated cpu > # host cpu. So when #emulated cpu < #host
cpu, the accuracy of timer emulation is the same with qemu. :-)

2012/5/22 Chen Yufei <cyf...@gm...>

> We implemented 2 versions of time measurement in x86 guest application,
>
> - gettimeofday
> - rdtsc
>
>
> When the emulated core is less then available physical cores, the time
> reported by the both time measurement are almost the same.
>
> --
> Best regards,
> Chen Yufei
>
>
> On 2012年5月22日Tuesday at 下午2:12, 任 wrote:
>
> > On Tue, May 22, 2012 at 02:05:57PM +0800, zhaoguo wang wrote:
> > > Arm can just emulate up to 4 core.
> > > When the number of cores emulated by COREMU is not more than the
> number of
> > > physical cpus, time is correct.
> > > So for Arm emulation, we don't use rdtsc.
> >
> >
> >
> > You mean the result of `time` is correct under the prerequisite tou
> mentioned?
> > How do you know it's correct, I mean any golden standard you compare
> with?
> >
> > Thanks. ;)
> >
> > Regards,
> > chenwj
> >
> > --
> > Wei-Ren Chen (任)
> > Computer Systems Lab, Institute of Information Science,
> > Academia Sinica, Taiwan (R.O.C.)
> > Tel:886-2-2788-3799 #1667
> > Homepage: http://people.cs.nctu.edu.tw/~chenwj
> >
> >
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>
>
>


-- 
Zhaoguo Wang<http://ipads.se.sjtu.edu.cn/doku.php?id=pub:members:zhaoguo_wang>
Institute of Parallel and Distributed Systems <http://ipads.se.sjtu.edu.cn/>