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

From: Ron Peacetree <rjpeace(at)earthlink(dot)net>
To: Bill Moran <wmoran(at)collaborativefusion(dot)com>,pgsql-performance(at)postgresql(dot)org
Subject: Re: Large (8M) cache vs. dual-core CPUs
Date: 2006-04-25 21:09:53
Message-ID: 26953267.1145999393194.JavaMail.root@elwamui-mouette.atl.sa.earthlink.net (view raw or flat)
Thread:
Lists: pgsql-performance
As others have noted, the current price/performance "sweet spot" for DB servers is 2S 2C AMD CPUs.  These CPUs are also the highest performing x86 compatible solution for pg.

If you must go Intel for some reason, then wait until the new NGMA CPU's (Conroe, Merom, Woodcrest) come out and see how they bench on DB workloads.  Preliminary benches on these chips look good, but I would not recommend making a purchase decision based on just preliminary benches of unreleased products.

If you must buy soon, then the decision is clear cut from anything except possinly a political/religious standpoint.
The NetBurst based Pentium and Xeon solutions are simply not worth the money spent or the PITA they will put you through compared to the AMD dual cores.  The new Intel NGMA CPUs may be different, but all the pertinent evidence is not yet available.

My personal favorite pg platform at this time is one based on a 2 socket, dual core ready mainboard with 16 DIMM slots combined with dual core AMD Kx's.

Less money than the "comparable" Intel solution and _far_ more performance.

...and even if you do buy Intel, =DON"T= buy Dell unless you like causing trouble for yourself.
Bad experiences with Dell in general and their poor PERC RAID controllers in specific are all over this and other DB forums.

Ron


-----Original Message-----
>From: Bill Moran <wmoran(at)collaborativefusion(dot)com>
>Sent: Apr 25, 2006 2:14 PM
>To: pgsql-performance(at)postgresql(dot)org
>Subject: [PERFORM] Large (8M) cache vs. dual-core CPUs
>
>
>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.
>
>Both of these are expensive bits of hardware, and I'm trying to
>gather as much evidence as possible before making a recommendation.
>The FreeBSD community seems pretty divided over which is likely to
>be better, and I have been unable to discover a method for estimating
>how much of the 2M cache on our existing systems is being used.
>
>Does anyone in the PostgreSQL community have any experience with
>large caches or dual-core pentiums that could make any recommendations?
>Our current Dell 2850 systems are CPU bound - i.e. they have enough
>RAM, and fast enough disks that the CPUs seem to be the limiting
>factor.  As a result, this decision on what kind of CPUs to get in
>the next round of servers is pretty important.
>
>Any advice is much appreciated.
>

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

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