Messages in this thread |  | | Subject | Re: [PATCH 2/9] x86/fpu: Hard-disable lazy fpu mode | From | Paolo Bonzini <> | Date | Wed, 5 Oct 2016 09:14:21 +0200 |
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On 05/10/2016 02:34, riel@redhat.com wrote: > From: Andy Lutomirski <luto@kernel.org> > > Since commit 58122bf1d856 ("x86/fpu: Default eagerfpu=on on all > CPUs") in Linux 4.6, eager FPU mode has been the default on all x86 > systems, and no one has reported any regressions. > > This patch removes the ability to enable lazy mode: use_eager_fpu() > becomes "return true" and all of the FPU mode selection machinery is > removed.
I haven't quite followed up on my promise to benchmark lazy vs. eager FPU, but I probably should do that now...
I see two possible issues with this. First, AMD as far as I know does not have XSAVEOPT. Second, when using virtualization, depending on how you configure your cluster it's enough to have one pre-SandyBridge Intel machine to force no XSAVE on all machines.
Thanks,
Paolo
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