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Subject: Re: Tables or Calculation

Author: David Rasmussen

Date: 02:23:54 01/18/03

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On January 18, 2003 at 05:19:14, Matt Taylor wrote:

>On January 18, 2003 at 05:02:44, David Rasmussen wrote:
>
>>On January 18, 2003 at 05:00:16, Matt Taylor wrote:
>>
>>>
>>>64-bit shift in something like 3 cycles when count is < 32. Pentium 4 L1 cache
>>>latency -- 2 clocks. Athlon L1 cache latency -- 3 clocks.
>>
>>I don't understand this
>
>Yeah, broken English is a bad thing. Here's how it breaks down:
>
>Shift form -- 3 cycles
>
>Table (Athlon) -- 3 cycles
>Table (Pentium 4) -- 2 cycles
>
>>>Bad performance of former indicitive of poor optimization.
>>
>>I don't understand this
>
>It means that the compiler is not doing its job. Perhaps there is an
>optimization switch you have not enabled. Perhaps your inline function is not in
>a header file where the C compiler can get at it. Perhaps the compiler just
>flops on 64-bit code.
>
>It means basically that something is wrong. There should be almost no difference
>in speed.
>
>-Matt

I see. It does about the same with both Intel C++ and MSVC 7




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