Dor Laor <dlaor <at> redhat.com> writes:
>
> On 06/25/2009 04:25 PM, Eran Rom wrote:
> > Behavior:
> > Running a code doing:
> > t1 = gettimeofday
> > t2 = gettimeofday
> > while t2-t1< 5 minutes {
> > sleep(1)
> > t2 = gettimeofday
> > }
> >
> > Ran it 10 times, each time in a 'newly launched' VM,
> > halting it after the test.
> > 8 out of 10 times the wall clock showed 5 minutes
> > 1 time 4 minutes and 40 seconds
> > 1 time 0 seconds
> >
>
> I'm not sure what's your 'wall clock' value,
> there is not printf in your
> script.
the 'wall clock' is host time.
Here is what I am doing form the host:
#! /bin/bash
date
ssh $GuestIP run_gettimeofday_binary
date
> Nevertheless, the tsc clock is not reliable,
> the host can scale it, or
> go into
> deep sleep state.
indeed my current clock source is tsc
>
> So either use newer kernel with kvmclock (pv)
> or change the clock source
> into rtc/pit
>
No rtc/pit in my available clock sources, however,
I assume its a question of kernel compilation parameters,
is that right?
What is the advantage of rtc/pit/kvmclock (pv)over tsc?
Also, is kvmclock (pv) better than the other two options.
the thing is that I am 'confined' to use 2.6.27,
and if I decide on kvmclock, i will need to add it
'manually'
Thanks,
Eran
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