Subj : Re: Windows issues
To   : Angus Mcleod
From : Deuce
Date : Fri Jun 10 2005 10:11 pm

  Re: Re: Windows issues
  By: Angus Mcleod to Finnigann on Fri Jun 10 2005 18:26:00

 >  > And the rest of the article said that if you have xx% free ram, you are
 >  > wasting xx%. Well that sort of makes sense, but not logically. Of course
 >  > I tend to trail back on the understanding parts.
 > 
 > Well, that is a matter for debate, but it is a fairly reasonable claim.
 > If all of your programs, all together (OS too), including code, data,
 > buffers, drivers and etc, come to (say) 200 meg of RAM and your system
 > contains 256 meg of physical RAM, then we can debate the advisability of
 > using larger buffers, etc, to utilize the extra RAM.  But if the total
 > memory requirements come to (say) 400 meg, and you only have 256 meg, you
 > are going to have to page out 144 meg worth of pages.  This will reduce
 > the pages in the working set of your process(es) to less than 100%.
 > Obviously, if you page out MORE than 144 meg, leaving free physical RAM in
 > the system but burdening your processes with even smaller working sets,
 > then you are wasting that free RAM.
 > 
 > So yes, if you have 80% RAM in use, then you are probably "wasteing" the
 > 20% of free physical RAM.  You should page in some of the pages in the
 > page file, in an attempt to make the processes run more efficiently (less
 > page faults).  Unless the page file is actually empty, in which case you
 > should actually SELL a few of your RAM sticks...  :-)

A simpler explination goes something like this...
You have 128MB of RAM... you are running two processes that each consume 64MB
or RAM.  One process is very active and the other is idle.  The active process
is doing many random read/writes to the disk.

Without paging, this means that none of the IO gets caches because there is no
free RAM.  If the idle task gets paged out, you then have 64MB of cache to
buffer the disk IO in which WILL increase performace.  When you switch back to
the idle task, there will be a noticeable flood of page faults, resulting in
something that LOOKS like poor performace but in actual fact gave BETTER
performace overall.

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