Messages in this thread | | | From | Andy Lutomirski <> | Date | Mon, 27 Oct 2014 08:30:22 -0700 | Subject | Re: [PATCH v2 8/8 only] x86,vdso: Use LSL unconditionally for vgetcpu |
| |
On Mon, Oct 27, 2014 at 4:31 AM, Andi Kleen <andi@firstfloor.org> wrote: > Andy Lutomirski <luto@amacapital.net> writes: > >> LSL is faster than RDTSCP and works everywhere; there's no need to >> switch between them depending on CPU. > > Yes it should have been done like this from day 1. > >> diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c >> index 9793322751e0..d14bb8faad16 100644 >> --- a/arch/x86/vdso/vclock_gettime.c >> +++ b/arch/x86/vdso/vclock_gettime.c >> @@ -11,6 +11,9 @@ >> * Check with readelf after changing. >> */ >> >> +/* Disable static_cpu_has debugging; it doesn't work in the vDSO */ >> +#undef CONFIG_X86_DEBUG_STATIC_CPU_HAS >> + >> #include <uapi/linux/time.h> >> #include <asm/vgtod.h> >> #include <asm/hpet.h> >> diff --git a/arch/x86/vdso/vgetcpu.c b/arch/x86/vdso/vgetcpu.c >> index add1d98d2477..fd8470c98ab5 100644 >> --- a/arch/x86/vdso/vgetcpu.c >> +++ b/arch/x86/vdso/vgetcpu.c >> @@ -5,10 +5,12 @@ >> * Fast user context implementation of getcpu() >> */ >> >> +/* Disable static_cpu_has debugging; it doesn't work in the vDSO */ >> +#undef CONFIG_X86_DEBUG_STATIC_CPU_HAS > > > These two hunks are unrelated? >
They're related, but they're no longer necessary. v1 of this patch added a static_cpu_has call to vgtod.h, breaking compilation if this hunk wasn't there.
I can send a v3 with these deleted, but I prefer keeping them, since they may save whomever modifies these files next a compiler error.
--Andy
> -Andi > > -- > ak@linux.intel.com -- Speaking for myself only
-- Andy Lutomirski AMA Capital Management, LLC
| |