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Re: Dual core Opterons beating quad core Xeons?

From: Gregory Stark <stark(at)enterprisedb(dot)com>
To: "Stuart Bishop" <stuart(at)stuartbishop(dot)net>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Dual core Opterons beating quad core Xeons?
Date: 2007-12-19 12:49:26
Message-ID: 87k5nan92h.fsf@oxford.xeocode.com (view raw or flat)
Thread:
Lists: pgsql-performance
"Stuart Bishop" <stuart(at)stuartbishop(dot)net> writes:

> For pgbench (PG 8.2 running Ubuntu), the Opteron is getting about 6x TPS
> over the Xeon (3000+ TPS on Opteron vs ~500 on Xeon). Things get a little
> better for Xeon with PG 8.3 (570-540 TPS).

There was a problem in the past which affected Xeons. But I thought it had
been mostly addressed. Xeons are (or were? these things are always changing)
more sensitive to interprocess contention due to their memory architecture
though.

What are you actually doing in these transactions? Are they read-only? If not
is fsync=off (which you don't want if you care about your data but you do if
you're trying to benchmark the cpu).

Are the crappy disks *identical* crappy disks? If they have different
controllers or different drives (or different versions of the OS) then you
might be being deceived by write caching on one set and not the other. If
they're not read-only transactions and fsync=on then the TPS of 3000+ is not
credible and this is likely.

-- 
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com
  Ask me about EnterpriseDB's RemoteDBA services!

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Subject: Re: Dual core Opterons beating quad core Xeons?
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