Messages in this thread | | | Date | Wed, 22 Aug 2012 10:47:02 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v2 2/2] x86/pat: Avoid contention on cpa_lock if possible |
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* Ido Yariv <ido@wizery.com> wrote:
> vSMP Foundation does not require to serialize CPA by guaranteeing that > the most recent TLB entry will always be used. > > To avoid needless contention on cpa_lock, do not lock/unlock it if it > isn't necessary. > > Based on work by Shai Fultheim <shai@scalemp.com>. > > Signed-off-by: Ido Yariv <ido@wizery.com> > Acked-by: Shai Fultheim <shai@scalemp.com> > --- > Changes from v1: > - Use a synthetic CPUID bit and a use static_cpu_has() as suggested by > H. Peter Avnin > > arch/x86/include/asm/cpufeature.h | 1 + > arch/x86/kernel/vsmp_64.c | 10 ++++++++++ > arch/x86/mm/pageattr.c | 30 +++++++++++++++++++++--------- > 3 files changed, 32 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h > index 6b7ee5f..92303a0 100644 > --- a/arch/x86/include/asm/cpufeature.h > +++ b/arch/x86/include/asm/cpufeature.h > @@ -97,6 +97,7 @@ > #define X86_FEATURE_EXTD_APICID (3*32+26) /* has extended APICID (8 bits) */ > #define X86_FEATURE_AMD_DCM (3*32+27) /* multi-node processor */ > #define X86_FEATURE_APERFMPERF (3*32+28) /* APERFMPERF */ > +#define X86_FEATURE_NO_CPA_LOCK (3*32+29) /* Serializing cpa is not required */
Patch looks mostly good, but could we please use some more hardware-ish name, instead of referring to a kernel lock?
I.e. how would you name it if this was a real hardware feature? Certainly not 'No CPA Lock'.
Thanks,
Ingo
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