Re: [cpuops cmpxchg V2 5/5] cpuops: Use cmpxchg for xchg to avoidlock semantics

From: H. Peter Anvin
Date: Tue Dec 14 2010 - 20:08:27 EST


On 12/14/2010 09:29 AM, Tejun Heo wrote:
> Hello,
>
> On 12/14/2010 06:22 PM, H. Peter Anvin wrote:
>> On 12/14/2010 09:19 AM, Christoph Lameter wrote:
>>>>
>>>> Is it genuinely faster to do the pre-load mov, or can we drop that too?
>>>> My guess would be that yes it is, but if it happens not to be it would
>>>> be nice to reduce the code size.
>>>
>>> Dropping the load increases the cycle count from 11 to 16.
>>
>> Great, that answers that! I'll pick up the patch hopefully today (I'm
>> finally ramping back up on arch/x86 again after having been diverted to
>> an internal project for a while...)
>
> How do you want to route these? All patches before this series is
> already in the percpu tree. I can pull the generic bits and leave out
> the x86 bits so that x86 tree can pull in percpu bits and then put x86
> stuff on top of it. If you wanna go that way, I would drop all x86
> related patches from the previous patchsets too.
>

It's probably easiest if you just add them with my Acked-by: then.
Alternatively, I could pick them up so they go into -tip and the tip
test machinery.

-hpa
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