RE: [Xen-ia64-devel] [PATCH] [Resend]Enable hash vtlb

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

> >> The attachment is the script which I used to get kernel 
> build performance.
> >> Usage Example,
> >> ./make_kernel.sh    2    /root/linux-2.6.16.tar.bz2
> >>                   (times of build)   (absolute path)
> >
> >   The attachment seems to have been lost to a virus 
> scanner.  My test
> >was simply:
> >
> Almost same
> Thanks
> Anthony
> 
> ># make clean
> ># time make > /dev/null 2>&1
> >repeat
> >
> >Thanks,
> >     Alex

I wonder if the time command is appropriate for measuring
performance in a domU?  Are we sure the "real" component
is measuring elapsed wall clock time?  If not, perhaps
"time" is not accounting for time spent in the hypervisor
and time spent in dom0 (e.g. backend drivers).

In all my past measurements, I've used "date +%s" before
and after and subtracted the difference.

Even if "time" checks out OK, I am still astonished if domU
is faster than native and suspect that there is something
wrong with either the measurement or the methodology.

Dan

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