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Re: Large (8M) cache vs. dual-core CPUs

From: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
To: Scott Marlowe <smarlowe(at)g2switchworks(dot)com>
Cc: Bill Moran <wmoran(at)collaborativefusion(dot)com>,pgsql-performance(at)postgresql(dot)org
Subject: Re: Large (8M) cache vs. dual-core CPUs
Date: 2006-04-26 22:14:47
Message-ID: 20060426221447.GZ97354@pervasive.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Wed, Apr 26, 2006 at 10:17:58AM -0500, Scott Marlowe wrote:
> On Tue, 2006-04-25 at 18:55, Jim C. Nasby wrote:
> > On Tue, Apr 25, 2006 at 01:33:38PM -0500, Scott Marlowe wrote:
> > > On Tue, 2006-04-25 at 13:14, Bill Moran wrote:
> > > > I've been given the task of making some hardware recommendations for
> > > > the next round of server purchases.  The machines to be purchased
> > > > will be running FreeBSD & PostgreSQL.
> > > > 
> > > > Where I'm stuck is in deciding whether we want to go with dual-core
> > > > pentiums with 2M cache, or with HT pentiums with 8M cache.
> > > 
> > > Given a choice between those two processors, I'd choose the AMD 64 x 2
> > > CPU.  It's a significantly better processor than either of the Intel
> > > choices.  And if you get the HT processor, you might as well turn of HT
> > > on a PostgreSQL machine.  I've yet to see it make postgresql run faster,
> > > but I've certainly seen HT make it run slower.
> > 
> > Actually, believe it or not, a coworker just saw HT double the
> > performance of pgbench on his desktop machine. Granted, not really a
> > representative test case, but it still blew my mind. This was with a
> > database that fit in his 1G of memory, and running windows XP. Both
> > cases were newly minted pgbench databases with a scale of 40. Testing
> > was 40 connections and 100 transactions. With HT he saw 47.6 TPS,
> > without it was 21.1.
> > 
> > I actually had IT build put w2k3 server on a HT box specifically so I
> > could do more testing.
> 
> Just to clarify, this is PostgreSQL on Windows, right?
> 
> I wonder if the latest Linux kernel can do that well...  I'm guessing
> that the kernel scheduler in Windows has had a lot of work to make it
> good at scheduling on a HT architecture than the linux kernel has.

Yes, this is on Windows XP. Larry might also have a HT box with some
other OS on it we can check with (though I suspect that maybe that's
been beaten to death...)
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby(at)pervasive(dot)com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

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