optimizing
performances *
> Limiting Windows' usage of disk cache
Why modify disk cache?
Windows' management of the disk cache isn't exactly the most efficient
method. Basically, it expands the disk cache when file system activity
is taking place, and shrinks it when memory is in more demand than the
disk. Sounds like a good idea, except for the fact that it will suck up
as much memory as it can at some times, fighting with applications for
physical RAM.
How it works
For an example, lets say you have a system with 64MB of RAM, and you are
copying a 100MB file from one hard drive to another. Windows will expand
the disk cache to fill all of available RAM that it can, because it thinks
that maybe you'll be reading from that file you just copied. It might
make the disk cache take up 10, 20, even 30 to 45MB of RAM. Right now
you've got 45MB for disk cache and Windows drivers and Kernel are probably
taking up the last 19MB (it happens). What happens when you go to start
up a RAM and disk (at least for the initial load) hungry application,
such as Photoshop 5.0 or Unreal, after copying that file? Thrash, thrash,
thrash goes the hard drive. Windows is very childish in letting up RAM
for it's disk cache. I remember on my K6-200, when I upgraded from 32MB
to 96MB RAM, Windows was grabbing lots of memory for the disk cache, and
I got the dreaded background picture page-in. Windows was hogging so much
RAM that my whole 600K background bitmap had to be paged in from disk,
which is something I used to get on a 386DX-25 with 4MB RAM in Windows
3.1.
What's next?
The idea is to llimit that disk cache! Basically, you want the minimum
amount of disk cache to be about 1MB (you always want some cache present),
and the maximum to be about 1/4 of your total memory. Here's a short table
for quick reference ...
RAM
|
8Mb
|
16Mb
|
24Mb
|
32Mb
|
48Mb
|
64Mb
|
96Mb
|
128Mb
|
Cache Max.
|
2048
|
4096
|
6144
|
8192
|
12288
|
16384
|
24576
|
32768
|
Procedure
Now, here's what you do to limit your disk cache size
>Windows98 and above: Click Start, Run... then type in msconfig.
Validate. Click the system.ini tab.
>Earlier versions: Click Start, Run... then type in notepad
c:\windows\system.ini. Validate.
Now find the section called [vcache] which is near the end. Modify it
to look like this, substituting your value for the Maximum:
[vcache]
MaxFileCache=32768
MinFileCache=1024
Save the file, close Notepad, and restart your system. And just so you
know, "MinFileCache" and "MaxFileCache" have to be greater than zero.
*
The Knights of Boot© disclaim any responsibility for any damage arising
as a result of the implementation of these instructions.
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