Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Source code to measure it

Author: Gerd Isenberg

Date: 14:14:45 07/15/03

Go up one level in this thread


On July 15, 2003 at 09:33:39, Robert Hyatt wrote:

>On July 15, 2003 at 06:24:58, Vincent Diepeveen wrote:
>
>>On July 14, 2003 at 16:07:27, Robert Hyatt wrote:
>>
>>You measure the latency with those benches of sequential reads.
>
>No.  lm-bench does _random_ reads and computes the _random-access_
>latency.
>
>Don't know why you have a problem grasping that.
>
>
>>So already opened cache lines you can get data faster from than
>>random reads to memory.
>
>That also makes no sense.  Perhaps you mean "already opened memory
>rows"?
>
>
>>
>>Random reads to memory are about 280 ns at single cpu P4 and about 400ns at dual
>>P4s.
>
>No they aren't.
>

Bob, i found nothing wrong with Vincent's code. He does N-random hashreads and
aggregates the time used. I thought about some factor 2 error - but found no one
so far. Random Hashreads, like chess programs do.

1e9 random hash reads take 265 seconds (including ~60 seconds overhead) on my
athlon-pc, however latency is defined. Any explanation? Any systematical error
or assumption? What does lm-bench do, to measure latency?

Regards,
Gerd





This page took 0.06 seconds to execute

Last modified: Thu, 07 Jul 11 08:48:38 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.