lkml.org 
[lkml]   [2014]   [Oct]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [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


\
 
 \ /
  Last update: 2014-10-27 17:01    [W:0.038 / U:0.700 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site