From: Leigh Dyer <leigh@eclinic.com.au>
To: mark@mark.mielke.cc
Cc: Scott Marlowe <smarlowe@g2switchworks.com>
Cc: Bill Moran <wmoran@collaborativefusion.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Large (8M) cache vs. dual-core CPUs
Date: Wed, 26 Apr 2006 11:53:06 +1000
Message-ID: <444ED282.6010102@eclinic.com.au> (raw)
In-Reply-To: <20060426011701.GB12711@mark.mielke.cc>
References: <20060425141435.6c8c163c.wmoran@collaborativefusion.com>
<1145990018.23538.234.camel@state.g2switchworks.com>
<20060425183817.GA9241@mark.mielke.cc>
<1145990551.23538.244.camel@state.g2switchworks.com>
<20060426005440.GA12711@mark.mielke.cc>
<20060426011701.GB12711@mark.mielke.cc>
mark@mark.mielke.cc wrote:
> Another benefit of Pentium D over AMD X2, at least until AMD chooses
> to switch, is that Pentium D supports DDR2, whereas AMD only supports
> DDR. There are a lot of technical pros and cons to each - with claims
> from AMD that DDR2 can be slower than DDR - but one claim that isn't
> often made, but that helped me make my choice:
>
They're switching quite soon though -- within the next month now it
seems, after moving up their earlier plans to launch in June:
http://www.dailytech.com/article.aspx?newsid=1854
This Anandtech article shows the kind of performance increase we can
expect with DDR2 on AMD's new socket:
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2741
The short version is that it's an improvement, but not an enormous one,
and you need to spend quite a bit of cash on 800Mhz (PC6400) DDR2 sticks
to see the most benefit. Some brief local (Australian) price comparisons
show 1GB PC-3200 DDR sticks starting at just over AU$100, with 1GB
PC2-4200 DDR2 sticks around the same price, though Anandtech's tests
showed PC2-4200 DDR2 benching generally slower than PC-3200 DDR,
probably due to the increased latency in DDR2.
Comparing reasonable quality matched pairs of 1GB sticks, PC-3200 DDR
still seems generally cheaper than PC2-5300 DDR2, though not by a lot,
and I'm sure the DDR2 will start dropping even further as AMD systems
start using it in the next month or so.
One thing's for sure though -- Intel's Pentium D prices are remarkably
low, and at the lower end of the price range AMD has nothing that's even
remotely competitive in terms of price/performance. The Pentium D 805,
for instance, with its dual 2.67Ghz cores, costs just AU$180. The X2
3800+ is a far better chip, but it's also two-and-a-half times the price.
None of this really matters much in the server space though, where
Opteron's real advantage over Xeon is not its greater raw CPU power, or
its better dual-core implementation (though both would be hard to
dispute), but the improved system bandwidth provided by Hypertransport.
Even with Intel's next-gen CPUs, which look set to address the first two
points quite well, they still won't have an interconnect technology that
can really compete with AMD's.
Thanks
Leigh
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To: pgsql-performance@postgresql.org
Cc: leigh@eclinic.com.au, mark@mark.mielke.cc, smarlowe@g2switchworks.com, wmoran@collaborativefusion.com
Subject: Re: Large (8M) cache vs. dual-core CPUs
In-Reply-To: <444ED282.6010102@eclinic.com.au>
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