Messages in this thread | | | Date | Wed, 25 Feb 2015 11:50:20 +0100 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH] x86, fpu: Use eagerfpu by default on all CPUs |
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* Borislav Petkov <bp@alien8.de> wrote:
> On Tue, Feb 24, 2015 at 04:07:07PM -0800, Andy Lutomirski wrote: > > > I'd prefer a different partial solution: encourage > > everyone to clear the xstate before making syscalls > > (using e.g. vzeroall). In fact, maybe user code should > > aggressively clear newly-unused xstate. > > We don't trust userspace.
We certainly don't, but in this case it's a performance optimization detail: if user-space clears unused xstate in a way that the CPU recognizes it (for example VZEROALL) then it might get faster context switches.
Thanks,
Ingo
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