Messages in this thread | | | Date | Fri, 29 May 2015 20:51:34 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 02/19] x86, fpu: Wrap get_xsave_addr() to make it safer |
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* Borislav Petkov <bp@alien8.de> wrote:
> On Thu, May 28, 2015 at 06:05:33PM -0700, Andy Lutomirski wrote: > > I would propose that we take the opposite approach and just ban > > eagerfpu=off when MPX is enabled. We could then take the next step > > and default eagerfpu=on for everyone and, if nothing breaks, then just > > delete lazy mode entirely. > > > > I suspect we'd have to go back to Pentium 3 or earlier to find a CPU > > on which lazy mode is actually a good idea. > > Last time I checked (and ran some benchmarks) it was only a minute > slowdown so I say we kill lazy mode if it means significant code > complexity drop. > > Can I also emulate Greg here and suggest that Pentium 3 people should > buy newer hw? They should think about the environment, if nothing else. > > :-P
I went back as far as Athon64 and the CR0 manipulation and CR0 faults are overly expensive there too.
Ok, you guys convinced me, I'll do a patch for this in tip:x86/fpu, and then people can benchmark it.
Thanks,
Ingo
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