-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 01/16/2015 10:54 AM, Oleg Nesterov wrote: > On 01/15, Rik van Riel wrote: >> >> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 >> >> On 01/15/2015 02:20 PM, Oleg Nesterov wrote: >>> b/arch/x86/kernel/i387.c @@ -81,9 +81,7 @@ void >>> __kernel_fpu_begin(void) this_cpu_write(in_kernel_fpu, true); >>> >>> if (__thread_has_fpu(me)) { - __thread_clear_has_fpu(me); >> >> I will put that line back in the patch series that defers the >> loading of FPU state until the switch to user space, > > I think this needs more discussion. > > Firstly, __thread_clear_has_fpu() should go into > __kernel_fpu_end(), it should replace restore_fpu_checking(). > > But does your series actually need this change? Correctness-wise > this is not needed (afaics). Performance-wise I am not sure, > kernel_fpu_begin() is unlikely event. Plus I am not sure this is a > win (in general), but I can be easily wrong.
__kernel_fpu_begin() / __kernel_fpu_end() are used all the time when running KVM guests. The KVM VCPU thread has both a user space and a guest VCPU state. Generally the VCPU thread stays in the kernel, and rarely (if ever) exits to user space. >> but I guess we can go either way for now... > > Yes, this should not really conflict with your changes in any > case. > > Given that you acked 1/3 and 3/3, perhaps you can ack this one as > well? Sure, we can figure out the cleanest thing to do for KVM later on. Lets get these cleanups merged first. Acked-by: Rik van Riel <r...@redhat.com> - -- All rights reversed -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEbBAEBAgAGBQJUuTcmAAoJEM553pKExN6DJJMH+IjE3w+9UJ29AgE5Nw11qG86 5CgsxQ9T2CuzysW3a3HxRssjjPRtYeU1acDlQ0QMl6SKRw73wgy1kcZ22qEN1hSF jKxSmkOgMWtUejJTRVKwHuKwG53BMiT/ZfSy8sIDtKOJ6HWZrHFCtvacGQ/tIjDF gtfmUzZ2tfiJaYXYhdUlYDssKbI1lh/BMp3Y7vW6h5doDJL/KIKALlGWlI1Arsjl Ns3SCvcztw8ojJnHK9tuK6ngAz9fkVJtef6+r59ITdcO1++lE8a73xLwg+FUDj4v wlHz2gkYDjuLCNrahnplJHIuTV6LXR1FWiAFh6MElt7qejSUmcSxKudwhncdIw== =GbZ2 -----END PGP SIGNATURE----- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/