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Subject: Re: Hammer info. And som SMP musings.

Author: Vincent Diepeveen

Date: 06:49:34 03/24/02

Go up one level in this thread


On March 24, 2002 at 00:00:30, Robert Hyatt wrote:

>On March 23, 2002 at 17:21:10, Slater Wold wrote:
>
>>On March 23, 2002 at 17:07:53, Sune Fischer wrote:
>>
>>>On March 23, 2002 at 15:58:19, Tom Kerrigan wrote:
>>>
>>>>On March 23, 2002 at 09:53:13, Dan Andersson wrote:
>>>>
>>>>>As seen in:
>>>>>http://www.aceshardware.com/read.jsp?id=45000312
>>>>>A chess program using traditional work scheduling algorithms will not be using
>>>>>the Hammer architecture at its most effective. But it won't be all that bad due
>>>>>to the HyperTransport tunnels. And high bandwidth memory. A funny consequence of
>>>>>the architecture is that SMP multiprocessing is achieved by having software
>>>>>drivers.
>>>>
>>>>I don't know what you mean by "traditional work scheduling algorithms" but the
>>>>Hammer will be great for running chess programs out of the box. The only way to
>>>>make it faster would be to recompile the programs for x86-64, which reportedly
>>>>yields a 10-15% performance gain.
>>>
>>>The Hammer is a 64-bit chip, I expect it to bring a lot more than just 10-15% in
>>>chess, more like 100-150% for those progs with bitboards.
>>>
>>>-S.
>>
>>You're dreaming.  Alpha's don't get *anywhere* near that kind of gain.  More
>>like the 10-15% that Tom said.
>>
>
>
>Depends.  Tim Mann produced > 1M nodes per second on a 600mhz alpha.  NO
>600 mhz Intel will come within 1/2 that total...

http://www.specbench.org/cgi-bin/osgresults?conf=cint2000

the fastest Alpha:

http://www.specbench.org/osg/cpu2000/results/res2001q4/cpu2000-20011022-01046.html

4 CPUs in total 8 MB L2 cache each cpu, and 1 cpu enabled,
which means probably that the cpu running crafty benchmark
was PROFITTING from the other 3 cpu's L2 cache too (classical trick)

So it was using in total 32MB L2 cache where 1 cpu has 8 MB.

Despite that at 1 Ghz its performance for crafty base runtime is 122.

Note this is a very recent test. November 2001.

Now latest result for K7 processors which are 32 bits:

http://www.specbench.org/osg/cpu2000/results/res2002q1/cpu2000-20020114-01202.html

So this is a single cpu system. No cheating doing test on a quad like
alpha did (or SUN/IBM keep doing).

Base runtime 102.

So in short alpha 1Ghz with 64 bits registers and
4 instructions a clock and cheating with L2 cache it
all results in being 100% x (122/102) (minus 100%) = 19.6% slower
than a processor clocked single cpu at 1.667Ghz

Relative to the 1.67Ghz from the K7 the alpha achieves like
a 102/122 x 1.667Ghz = 1.394Ghz K7

In theory the 4 instructions a clock for alpha versus
3 instructions a clock for K7 give 33% speedup:

1.000 Ghz + 33% = 1.333Ghz

It achieves however 1.394Ghz

In short i am missing the speedup for being 64 bits at all!








>
>
>>>
>>>>-Tom



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