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Subject: Re: is the

Author: Dan Newman

Date: 11:00:46 07/21/98

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On July 21, 1998 at 09:00:29, Roberto Waldteufel wrote:

>Hi Dan,
>Now that you mention it, the OS may well be partly responsible. This reminds me
>of a peculiarity I have noticed running my program under Windows95. The program
>uses about 44 MB RAM for storage, but my machine has 64MB which should be more
>than enough spare to keep Windows happy. When I first load my program,
>everything is fine. When I start play, the program thrashes the hard disk for
>about 15 seconds, during which time the program runs very slowly. Afterwards
>everything is fine. If I then quit the program and reload it, this disk access
>does not occur again, but if I run another application in between, then I get
>the disk thrashing at startup again. I know virtually nothing about Windows,
>having only recently switched from DOS so as to use 32-bit code, but it seems as
>if Windows is swapping a lot of stuff out of RAM to make room for the program
>data while the program is actually running!
>Best wishes,

Hi Roberto,

I've seen this too, while running matches between my program and Comet
or Crafty using Winboard.  It's kind of annoying when the flag falls on
you and you haven't even made your first book move...  I think Win95's
swap algorithm must be pretty poor--but I can't quite figure out what
it needs to swap out.  Perhaps it has Windows code and data scattered
all over memory and when allocating the large chunk(s) of contiguous
memory needed for the hash table(s) it decides to swap itself out to
disk--of course it swaps out something that it needs, so it must swap
itself back in, and so on, thrashing all the way.  With virtual memory
you should be able to get "contiguous" memory without it really being
contiguous though...  Very mysterious.  Maybe Win98 does this better--
I've recently installed it, so I'll see if I can get it to swap for a
full minute now.


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