Re: [GENERAL] Opteron vs. Xeon performance differences
On Fri, 10 Oct 2008, Bart Grantham wrote: The Opterons are 2220 SE's, the Xeons are 5450's I think (family 15, model 6). Xeon - 3056 MB in 2.00 seconds = 1527.85 MB/sec Opteron - 4944 MB in 2.00 seconds = 2472.50 MB/sec There's something wrong with that Xeon system. That number should be twice that and your Xeon smoking those Opterons by 25% or so on benchmarks. My Q6600 system at home has a slower bus and clock speed than your Xeon, but hits 3891MB/s on cached hdparm even with the slowest of the RAM I have here. Now that I got the first round right, can I make a double or nothing bet that your Xeon system is either a) not running your RAM in dual-channel mode or b) is getting throttled by power management? Should I cross post to pgsql-performance? Or are most of the people on that list here, too? That would have been a better place to start at, but don't bother switching now--there's a lot of overlap. Cross-posting to the lists here is bad, partly because then replies by people who only belong to one of the two end up bugging the list admins. One of these days I'm going to summarize the main lore on this topic into a Wiki article anyway, which will pull the good stuff out of here regardless of the originating list. -- * Greg Smith [EMAIL PROTECTED] http://www.gregsmith.com Baltimore, MD -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Opteron vs. Xeon performance differences
On Thu, Oct 9, 2008 at 3:34 PM, Bart Grantham [EMAIL PROTECTED] wrote: Forgive me if this has been beaten into the ground, but my team and I couldn't find much conclusive study or posts on this issue. To make a long story short: we're experiencing Xeons as 50% slower than Opterons, even when the Xeon has twice as much cache and a slight clock speed advantage. I'm not sure what causes this issue either, although I suspect it's the inter-CPU / CPU to memory communication speeds that make the difference. It seems that as the number of CPUs increase, the opteron lead increases over the xeon. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Opteron vs. Xeon performance differences
How do you manage the wal in both servers? The version kernel is the same in both? Runs the same services? Do you make some test with Posgresql only in both servers? If the problem is the inter-CPU, i know you can specified the number of processors do you want to run dedicated to one process. 2008/10/10 Scott Marlowe [EMAIL PROTECTED]: On Thu, Oct 9, 2008 at 3:34 PM, Bart Grantham [EMAIL PROTECTED] wrote: Forgive me if this has been beaten into the ground, but my team and I couldn't find much conclusive study or posts on this issue. To make a long story short: we're experiencing Xeons as 50% slower than Opterons, even when the Xeon has twice as much cache and a slight clock speed advantage. I'm not sure what causes this issue either, although I suspect it's the inter-CPU / CPU to memory communication speeds that make the difference. It seems that as the number of CPUs increase, the opteron lead increases over the xeon. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Opteron vs. Xeon performance differences
Bart Grantham wrote: Forgive me if this has been beaten into the ground, but my team and I couldn’t find much conclusive study or posts on this issue. To make a long story short: we’re experiencing Xeons as 50% slower than Opterons, even when the Xeon has twice as much cache and a slight clock speed advantage. Simple question, you know that the plans are the same? And I don't think you said conclusively that it's the same version of PGSQL on both servers? -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Opteron vs. Xeon performance differences
On Thu, 9 Oct 2008, Bart Grantham wrote: The full story: we have an older production server with 2G of RAM, 2.4GHz Opterons w/ 1M of cache...The newer servers have 4G of RAM, 3.0GHz Xeons with 2M of cache. Model numbers please? I can probably guess for the Opterons, there are a lot of different implementations lumped under the Xeon brand name. Have you taken compared how fast the RAM is in the two systems? We were just talking about a similar unexpected performance different yesterday on another list: http://archives.postgresql.org/pgsql-performance/2008-10/msg00051.php I'd be curious what memtest86+ and the simple hdparm -T benchmark say about the two servers. If those numbers correlate with the performance difference you're seeing, the PostgreSQL code might have nothing to do with it. I've seen a 60% performance difference just between the best and worst RAM I tried on a single motherboard recently. -- * Greg Smith [EMAIL PROTECTED] http://www.gregsmith.com Baltimore, MD -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Opteron vs. Xeon performance differences
Bart Grantham wrote: a long story short: we're experiencing Xeons as 50% slower than Opterons, even when the Xeon has twice as much cache and a slight clock speed advantage. tests I finally took the final leap: just pull the disks and throw them in a newer Opteron chassis (2.8GHz, 1M cache). And whaddya know? It's got a 20% speed edge on the older Opteron, and blows away the performance of the newer Xeons. But is the difference in cpu or disk? Do the two machines get a similar disk transfer rate? Same raid card and disks in both machines, do they get the same MB/Sec? (as opposed to on-board controllers) -- Shane Ambler pgSQL (at) Sheeky (dot) Biz Get Sheeky @ http://Sheeky.Biz -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Opteron vs. Xeon performance differences
When i question about WAL, i mean if WAL is in other drive. You must run a benchmark more expensive to cpu for make a conclusion. Make a query that have more of 8 seconds, then you can see really if exists a diference in other way... i think you don't use the same image of the old server in the new. In that way could be a configuration kernel. do you make a test of hardware instead postgres?? if the hard give you better numbers, so postgres have the problem. 2008/10/10 Shane Ambler [EMAIL PROTECTED]: Bart Grantham wrote: a long story short: we're experiencing Xeons as 50% slower than Opterons, even when the Xeon has twice as much cache and a slight clock speed advantage. tests I finally took the final leap: just pull the disks and throw them in a newer Opteron chassis (2.8GHz, 1M cache). And whaddya know? It's got a 20% speed edge on the older Opteron, and blows away the performance of the newer Xeons. But is the difference in cpu or disk? Do the two machines get a similar disk transfer rate? Same raid card and disks in both machines, do they get the same MB/Sec? (as opposed to on-board controllers) -- Shane Ambler pgSQL (at) Sheeky (dot) Biz Get Sheeky @ http://Sheeky.Biz -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
