Scott Marlowe wrote: > For 2 sockets Intel rules the roost. I'd imagine AMD's much faster > bus architecture for >2 sockets would make them the winner, but I > haven't had a system like that to test, either Intel or AMD. > AMD has been getting such poor performance due to the RAM they've been using (DDR2-800) that it really doesn't matter--Intel has been thrashing them across the board continuously since the "Nehalem" processors became available, which started in volume in 2009. Intel systems with 3 channels of DDR3-1066 or faster outperform any scale of AMD deployment on DDR2, and nowadays even Intel's chapter desktop processors have 2 channels of DDR3-1600 in them. That's been the situation for almost 18 months now anyway. AMD's new "Magny-Cours" Opterons have finally adopted DDR3-1333, and closed the main performance gap with Intel again. Recently I've found the "Oracle Calling Circle" benchmarking numbers that Anand runs seem to match what I see in terms CPU-bound PostgreSQL database workloads, and the latest set at http://it.anandtech.com/show/2978/amd-s-12-core-magny-cours-opteron-6174-vs-intel-s-6-core-xeon/8 show how the market now fits together. AMD had a clear lead when it was Xeon E5450 vs. Opteron 2389, Intel pulled way ahead with the X5570 and later processors. Only this month did the Opteron 6174 finally become competitive again. They're back to being only a little slower at two sockets, instead of not even close. A 4 socket version of the latest Opterons with DDR3 might even unseat Intel on some workloads, it's at least possible again. Anyway, returning to "context switching on Xeon", there were some specific issues with the older PostgreSQL code that conflicted badly with the Xeons of the time, and the test case Tom put together was good at inflicting the issue. There certainly are still potential ways to have the current processors and database code run into context switching issues. I wouldn't expect that particular test case would be the best way to go looking for them though, which is the reason I highlighted its age and general obsolescence. -- Greg Smith 2ndQuadrant US Baltimore, MD PostgreSQL Training, Services and Support greg@xxxxxxxxxxxxxxx www.2ndQuadrant.us -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
