Re: [Xen-devel] Re: [PATCH 3/5] x86/pvclock: add vsyscall implementation

Jeremy Fitzhardinge
2009-10-27T18:20:07Z

On 10/27/09 10:29, Dan Magenheimer wrote:
> Is there any way for an application to conclusively determine
> programmatically if the "fast vsyscall" pvclock is functional
> vs the much much slower gettimeofday/clock_gettime equivalents?
>
> If not, might it be possible to implement some (sysfs?)
> way to determine this, that would also be backwards compatible
> to existing OS's that don't have pvclock+vsyscall supported?
>

It would probably be simplest and most portable for the app to just
measure the performance of gettimeofday and see if it meets its needs.

J