[PATCH 2/2] Add VDSO version of sched_getcpu on powerpc

[Carlos O'Donell]

On 01/07/2013 04:23 PM, Ryan S. Arnold wrote:
> On Sun, Jul 8, 2012 at 8:28 PM, Anton Blanchard <anton@samba.org> wrote:
>>
>> The kernel patch has been submitted and is in the review process.
>> Results on a POWER7 show the speedup of a sched_getcpu call:
>>
>> baseline: 538 cycles
>> vdso:      30 cycles
>>
>> 2012-07-09  Anton Blanchard  <anton@samba.org>
>>
>>         * sysdeps/unix/sysv/linux/powerpc/sched_getcpu.c: New file.
>>         * sysdeps/unix/sysv/linux/powerpc/Versions: Add __vdso_getcpu
>>         * sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h: Likewise.
>>         * sysdeps/unix/sysv/linux/powerpc/init-first.c: Likewise.
>>
> 
> This tests out fine.  I'm pretty sure that we don't need to check for
> kernel availability (e.g., __ASSUME).

Ensuring you have the feature available is an important 
part of the patch :-)

If the minimum kernel version is new enough that you 
are guaranteed to have the feature then you don't 
need to use an __ASSUME_* macro.

Cheers,
Carlos.