Messages in this thread | | | Date | Wed, 22 Aug 2012 12:07:55 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v2 2/2] x86/pat: Avoid contention on cpa_lock if possible |
| |
* Ido Yariv <ido@wizery.com> wrote:
> Hi Ingo, > > On Wed, Aug 22, 2012 at 10:47:02AM +0200, Ingo Molnar wrote: > > > > * 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? > > Sure thing. How about X86_FEATURE_TLB_RELIABLE?
Yeah, something like that. Maybe hpa can think of something better?
Thanks,
Ingo
| |