=|[ Larc's ]|= said:
On Fri, 28 May 2004 09:09:56 +0100, "Doug Ramage"
| Some thoughts on pagefile/swapfile settings for XP:
|
http://www.aumha.org/win5/a/xpvm.htm
Its a fine link, but its scope is not for advanced users or system
administrators. (moreso the horse talk
It doesnt recognise, that in this era of plentiful RAM *and* lagging Hard
Drive performance, the old hard drive paging operations are no longer
necessary, and with larger common memory usage, much more memory needs
passed through i/o than was the case when machines commonly ran with less
than 48 megs ram.
A number of authors writing about pagefiles state somewhat arrogantly that
no benefit could possibly be gained from limiting the size of the pagefile,
or virtualising it altogether.
For the advanced user or system builder, the great benefit available is to
free i/o from paging bandwidth (particularly desirable on laptops), and
free the OS from associated lags.
The purpose of setting maximum values on computer resources is to limit
undesired awol circumstances ability to make a mess of everything, flagging
the critical situation before they do. With enough global resource to
accomodate the greediest valid usuage possible, it is detrimental to set
maximum usage beyond that calculatd level (especialy pagefile because
larger pagefile = more i/o work).
On win2k if you set pagefile to 1.5 x RAM minimum, it will begin to
increase when about 90% of virtual memory is used, setting it below that
ratio causes windows to complain about its VM usuage long before its
reaching the estimated ceiling.
If you start with 256 meg of system ram, and allocate 512 megs min+max of
hard drive space for pagefile. That gives the system about 1250 megs
virtual memory (routinely compressed) - which for most users is much more
than enough required for any practical combination of open applications
-including modest CAD and graphic apps which often make more efficent use
of scratch disks that windows VM.
If you have 768 megs of system ram, windows will complain (..is increasing
virtual memory..) if you set pagefile to less than [768 x 1.5] = 1.1 gigs,
so youll have well over 2 gigs of virtual memory!
- for most users that is just a silly allocation of resources and the
relationship between mem and pagefile means youll be mirroring huge swathes
of virtual memory to your huge pagefile - on the cherished hard drive /
through limited i/o bandwidth...
The load on the hardrive and folly of the allocation increases the more
lovely onboard memory you give windows to deal with.
768 megs system memory is a decent sweet spot, if you take 512 megs off
windows and leave it 256 megs to work in, put the pagefile on a capable
ramdisk (or buy a pci card for $1000's)
Then you get much more than enough VM for all but the heaviest workstation
loads, have a perfectly smooth machine and completely free hard drive i/o,
and asociated power saving on laptops.
Programs DO load faster, and lags ARE eliminated, because decent ramdrives
do i/o transactions in ~no time at all.
The type of summarisations that technical authors often make about this
system are oversimplified to the point of being quite irrelevant to the
behaviour of the actual system (also see politicians, economists...
- so beware those who want dont wish to mislead in that way, its more
useful to understand the details by actualy observing them.
Regards,
