On 4/23/10, Tom Lane <t...@sss.pgh.pa.us> wrote: > Marko Kreen <mark...@gmail.com> writes: > > Um, you have been burned by exactly this on x86 also: > > http://archives.postgresql.org/pgsql-hackers/2009-03/msg01265.php > > > Yeah, we never did figure out exactly how come you were observing that > failure on Intel-ish hardware. I was under the impression that Intel > machines didn't have weak-memory-ordering behavior. > > I wonder whether your compiler had rearranged the code in ProcArrayAdd > so that the increment happened before the array element store at the > machine-code level. I think it would be entitled to do that under > standard C semantics, since that ProcArrayStruct pointer isn't marked > volatile.
Sounds likely. Which seems to hint its better to handle all processors as weak ordered and then work with explicit locks/memory barriers, than to sprinkle code with 'volatile' to supress optimizations on intel and then still fail on non-intel. -- marko -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
