Messages in this thread | | | From | Len Brown <> | Date | Mon, 24 May 2021 14:24:54 -0400 | Subject | Re: [PATCH v5 28/28] x86/fpu/amx: Clear the AMX state when appropriate |
| |
On Mon, May 24, 2021 at 1:39 PM Dave Hansen <dave.hansen@intel.com> wrote:
> >> might be considered nasty.
> > I'm not excited about burdening the generic idle path with a CPU > > feature specific check that would need to be checked on every idle > > entry. > > Me neither. > > But, the check itself should be cheap. A cpu_feature_enabled(AMX) check > will eliminate even the cost of a branch on systems without AMX. You > could probably even get fancy and also use a static branch that doesn't > get enabled until the first AMX user shows up.
It isn't just the hardware run-time cost. It is the source code complexity. That code is 100% generic.
Len Brown, Intel Open Source Technology Center
| |