Re: [PATCH] x86/cpuid: Fewer CPUID invocations in init_scattered_cpuid_features()

2018-01-24 Thread Borislav Petkov
On Tue, Jan 23, 2018 at 06:32:16PM +0100, Borislav Petkov wrote: > It's probably not even worth doing anything though - I doubt the speedup > is visible at all. One more thing I forgot to mention yesterday: I'm working on changing the CPUID parsing we do now and we'll probably end up simply readin

Re: [PATCH] x86/cpuid: Fewer CPUID invocations in init_scattered_cpuid_features()

2018-01-23 Thread Borislav Petkov
On Tue, Jan 23, 2018 at 02:53:33PM +, David Woodhouse wrote: > We were doing a fresh CPUID for every single bit in every single output > register. Do it once and then harvest *all* the bits we want. > > We were also doing the max_level check with a new CPUID invocation for > every single bit.

[PATCH] x86/cpuid: Fewer CPUID invocations in init_scattered_cpuid_features()

2018-01-23 Thread David Woodhouse
We were doing a fresh CPUID for every single bit in every single output register. Do it once and then harvest *all* the bits we want. We were also doing the max_level check with a new CPUID invocation for every single bit. Stop that too. Signed-off-by: David Woodhouse --- Spotted this in my trav