Re: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for)

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 21/09/2009 16:25, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> OK, I think I see the problem.
> 
> Since cs19506 "consistent_tscs" is a Xen boot parameter that
> defaults to disabled.  If the boot parameter is enabled and
> the boot cpu does NOT have X86_FEATURE_CONSTANT_TSC set,
> consistent_tscs gets re-disabled.
> 
> For my pvrdtscp scheme to work, consistent_tscs would need to
> be changed so that it defaults to enabled.
> 
> Jan, could you confirm that this solves the problem on your
> constant-TSC AMD box?
> 
> Keir, is there any reason that consistent_tscs shouldn't
> default to enabled?

There was some question whether it means what you think it means across NUMA
nodes. If we are sure that it does guarantee consistency across NUMA nodes
-- or if we don't care about that -- then it can be enabled by default.

 -- Keir



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel