On Mon, Jul 27, 2009 at 2:05 PM, Dave Youatt<dave@xxxxxxxxxxxxxxxxxxx> wrote: > On 01/-10/-28163 11:59 AM, Greg Smith wrote: >> On Tue, 21 Jul 2009, Doug Hunley wrote: >> >>> Just wondering is the issue referenced in >>> http://archives.postgresql.org/pgsql-performance/2005-11/msg00415.php >>> is still present in 8.4 or if some tunable (or other) made the use of >>> hyperthreading a non-issue. We're looking to upgrade our servers soon >>> for performance reasons and am trying to determine if more cpus (no >>> HT) or less cpus (with HT) are the way to go. >> >> If you're talking about the hyperthreading in the latest Intel Nehalem >> processors, I've been seeing great PostgreSQL performance from those. >> The kind of weird behavior the old generation hyperthreading designs >> had seems gone. You can see at >> http://archives.postgresql.org/message-id/alpine.GSO.2.01.0907222158050.16713@xxxxxxxxxxx >> that I've cleared 90K TPS on a 16 core system (2 quad-core >> hyperthreaded processors) running a small test using lots of parallel >> SELECTs. That would not be possible if there were HT spinlock >> problems still around. There have been both PostgreSQL scaling >> improvments and hardware improvements since the 2005 messages you saw >> there that have combined to clear up the issues there. While true >> cores would still be better if everything else were equal, it rarely >> is, and I wouldn't hestitate to jump on Intel's bandwagon right now. > > Greg, those are compelling numbers for the new Nehalem processors. > Great news for postgresql. Do you think it's due to the new internal > interconnect, that bears a strong resemblance to AMD's hypertransport [snip] as a point of reference, here are some numbers on a quad core system (2xintel 5160) using the old pgbench, scaling factor 10: pgbench -S -c 16 -t 10000 starting vacuum...end. transaction type: SELECT only scaling factor: 10 query mode: simple number of clients: 16 number of transactions per client: 10000 number of transactions actually processed: 160000/160000 tps = 24088.807000 (including connections establishing) tps = 24201.820189 (excluding connections establishing) This shows actually my system (pre-Nehalem) is pretty close clock for clock, albeit thats not completely fair..I'm using only 4 cores on dual core procs. Still, these are almost two years old now. EDIT: I see now that Greg has only 8 core system not counting hyperthreading...so I'm getting absolutely spanked! Go Intel! Also, I'm absolutely dying to see some numbers on the high end W5580...if anybody has one, please post! merlin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
