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


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