I ran a bit exhaustive pgbench on 2 test machines I have (quad dual core Intel and Opteron). Ofcourse the Opteron was much faster, but interestingly, it was experiencing 3x more context switches than the Intel box (upto 100k, versus ~30k avg on Dell). Both are RH4.0 64bit/PG8.1 64bit. Sun (v40z): -bash-3.00$ time pgbench -c 1000 -t 30 pgbench starting vacuum...end. transaction type: TPC-B (sort of) scaling factor: 1 number of clients: 1000 number of transactions per client: 30 number of transactions actually processed: 30000/30000 tps = 45.871234 (including connections establishing) tps = 46.092629 (excluding connections establishing) real 10m54.240s user 0m34.894s sys 3m9.470s Dell (6850): -bash-3.00$ time pgbench -c 1000 -t 30 pgbench starting vacuum...end. transaction type: TPC-B (sort of) scaling factor: 1 number of clients: 1000 number of transactions per client: 30 number of transactions actually processed: 30000/30000 tps = 22.088214 (including connections establishing) tps = 22.162454 (excluding connections establishing) real 22m38.301s user 0m43.520s sys 5m42.108s Thanks, Anjan -----Original Message----- From: Tom Lane [mailto:tgl@xxxxxxxxxxxxx] Sent: Tuesday, November 22, 2005 2:42 PM To: Anjan Dave Cc: Vivek Khera; Postgresql Performance Subject: Re: [PERFORM] High context switches occurring "Anjan Dave" <adave@xxxxxxxxxxx> writes: > Would this problem change it's nature in any way on the recent Dual-Core > Intel XEON MP machines? Probably not much. There's some evidence that Opterons have less of a problem than Xeons in multi-chip configurations, but we've seen CS thrashing on Opterons too. I think the issue is probably there to some extent in any modern SMP architecture. regards, tom lane
