Computer Chess Club Archives


Search

Terms

Messages

Subject: Importance of L2 cache speed/size for diff programs (was:..Genius speed?

Author: fca

Date: 01:48:56 08/12/98

Go up one level in this thread


On August 11, 1998 at 13:42:20, Moritz Berger wrote:

>On August 11, 1998 at 13:11:26, fca wrote:
>
>>>Higher NPS -> higher memory throughput -> less cache efficiency (just imagine a
>>>program that uses e.g. 64 KB hash and "lives" completely in the 512 KB 2nd level
>>>cache of a PII in comparison with Fritz which fills up hundreds of megabytes of
>>>hash tables in a couple of minutes).
>>
>>Put that way, seductive, Moritz. :-)
>>
>>But this case you conveniently quote is of course most highly and outrageously
>>unrepresentative.  At important time controls (ssdf, 40/2 and similar) how many
>>programs only use <= 512Kb hash !  CST?
>>
>>So I cannot tell one way or the other...
>>
>>We are talking about programs that all consume significantly more than 512Kb
>>hash - some absurdly more (F5 seems like an engine to fill memory with some sort
>>of data! ;-) )
>
>Very easy to verify: Just turn off 2nd level cache in your BIOS and see what
>happens. AFAIR Fritz was only about 30% slower without 2nd level cache, but I
>leave it up to you to post some exact data and correlate the effect on different
>programs.

:-)

I'll try this, but of course switching off L2 entirely *may* not properly
indicate the effect of a smaller or slower L2, which was what was being
discussed...

I really think this problem is complex.  When my faster machine arrives I can do
the tests on both (i.e. 166/256K and 450/512K) and will report.

I'd be interested, Moritz, to your views on Bob's reply to the above-quoted post
from me (August 11, 1998 13:11:26) in this thread.

I tend to agree with Bob - as you recall, the parentage of this discussion was
my surprise that such a huge speed ratio for Junior existed between the P200MMX
and P2/300, which others later attributed to L2-cache size/MHz.  I disagreed.

Kind regards

fca



This page took 0.01 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

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