On 28.10.2013 21:32, Andres Freund wrote:
> On 2013-10-28 15:02:41 -0400, Robert Haas wrote:
>> Most of the academic papers I've read on
>> implementing lock-free or highly-parallel constructs attempt to
>> confine themselves to 8-byte operations with 8-byte compare-and-swap,
>> and I'm a bit disposed to think we ought to try to hew to that as
>> well. I'm not dead set against going further, but I lean against it,
>> for all of the reasons mentioned above.
>
> I think there are quite some algorithms relying on 16byte CAS, that's
> why I was thinking about it at all. I think it's easier to add support
> for it in the easier trawl through the compilers, but I won't argue much
> for it otherwise for now.
Many algorithms require a 2*(pointer width) CAS instruction. On 64-bit
platforms that's 16 bytes, but on 32-bit platforms an 8 byte version
will suffice.
- Heikki