On 05/25/2011 01:34 PM, H.J. Lu wrote:
> On Wed, May 25, 2011 at 3:26 AM, Andrew Haley <a...@redhat.com> wrote:
>> On 05/24/2011 07:28 PM, H.J. Lu wrote:
>>
>>> This patch implements pause intrinsic suggested by Andi. OK
>>> for trunk?
>>
>> What does "full memory barrier" here mean?
>>
>> +@table @code
>> +@item void __builtin_ia32_pause (void)
>> +Generates the @code{pause} machine instruction with full memory barrier.
>> +@end table
>>
>> There a memory clobber, but no barrier instruction AFAICS. The
>> doc needs to explain it a bit better.
>
> There are read/load memory barrier, write/store memory barrier and
> full/general
> memory barrier. You can find them at
>
> http://www.kernel.org/doc/Documentation/memory-barriers.txt
>
> Should I include a pointer to it?
No. I know perfectly well what memory barriers are. I'm not asking
what "full memory barrier" means.
What barrier instruction(s) does __builtin_ia32_pause() generate?
All I see in the patch is "rep; nop". Is that really a full memory
barrier?
Andrew.
