system memory and L2 cache

[mark]

Is it true that too much memory slows down the computer?
I've read that a good rule of thumb is the following:

for each 256 kb of L2 cache you can have 256 MB of RAM.

That would mean for all single processor computers with
either AMD XP or Intel P4 chips, that would equate to an
ideal system RAM of 512 MB (assuming 512 kb of L2 cache)

Anyone know the definitive answer here?

thanks,

mark

 

[Bob I]

Never heard that before, and I've been at this a few years. Where did
you read this?

 

[Guest]

The title of the book is Iside Windows 2000 Server, by
William Boswell, published by New Riders. Pages 7 and
128. Something to do with virtual memory manager but it
was not well explained. And that's the only place I've
seen this.

mark

 

[Rob Stow]

Is it true that too much memory slows down the computer?
I've read that a good rule of thumb is the following:

for each 256 kb of L2 cache you can have 256 MB of RAM.

That would mean for all single processor computers with
either AMD XP or Intel P4 chips, that would equate to an
ideal system RAM of 512 MB (assuming 512 kb of L2 cache)

Anyone know the definitive answer here?

There used to be /some/ truth to that kind of reasoning
quite a few years ago. Older systems that had the
L2 cache on the motherboard often could only cache the
first "X" MB RAM -where "X" was typically 64 MB but
sometimes 256 MB.

On such a system, if your program and data were in RAM
somewhere after the first "X" MB, then you would in fact
take a performance hit relative to if they were in the
first "X" MB.

However, pretty much no system built in the days since
they moved the L2 cache from the motherboard and into
the processor suffers any such limitation. I think you
would have to go all the way back to the 80486 series.

 

[Guest]

Thanks for the info. Now I'll install that gig of RAM for
my client without apprehension.

mark

 

[Bob I]

From a real work standpoint I haven't seen that to be true given that
many servers have multiple gigs of ram.(which would infer multiple megs
of L2 cache)

 

[BeamGuy]

Well - not quite that far, the upper end of the Pentium classic
series has this quality...

 

[Rob Stow]

Well - not quite that far, the upper end of the Pentium classic
series has this quality...

Wasn't sure whether it was the 80486 or the Pentium.

The last Pentium system I dealt with was in service until about
one year ago and had an AOpen motherboard with no cache on the
motherboard. However, I also have a *very* vague recollection of
other Pentium systems in my past that might have had L2 on the
motherboard. It is all so long ago that the 8086-286-386-486-P-PII
stuff is mostly just one fuzzy memory.

As to limitations on the amount of RAM that could be dealt with
by the cache built into early Pentiums ... ugh - too long ago for
my brain after 20 years of beer and caffeine overdoses. I do recall
having to jump through some kind of hoop to get OS/2 to use more
than 64 MB, but I can't remember if the cache came into play for that.

 

[XMan]

Most of us had issues getting OS/2 to do anything valuable at all

Mike

 

[Rob Stow]

Most of us had issues getting OS/2 to do anything valuable at all

Until WinNT4 came along it was far superior to any server OS
MicroSoft had to offer. If you were coming from a Windows
background it might have seemed a little trickier to configure,
but once it was up and running it was easier to maintain, had
much better security, and had better user/server management
capabilities. IBM had been in the business of making server
OSes for a long time before MicroSoft joined the game - IBM
has been running for years while MicroSoft is still learning
to crawl.

Until Win98SE it was also a far better desktop OS. Not, perhaps,
for a non-techie home user, but certainly for businesses.
But then again, I still remember all the people I helped with
installing and configuring Win 2.x and 3.x on their home systems -
Windows at that time was also far from idiot proof also.
Heck, even today non-techie home users need lots of help with
modern Windows variants.

If IBM had chosen to keep OS/2 up-to-date, such as making it
capable of dealing with modern hardware, it would still
be far superior to anything MicroSoft has to offer.

Unfortunately MicroSoft won the race to the GUI-based OS market
when they pre-empted IBM with the release of Windows and they've
had the momentum ever since. App developers followed MicroSoft
and eventually IBM decided to let OS/2 wither on the vine.

And even though IBM took a little too long to bring OS/2 to
market, they still could have repaired a lot of the damage
if they had done a half decent job of marketing it.
Instead they chose to price it a 3 times the price of Windows,
did minimal advertising, and instead of demonstrating just
how much better it was than Windows they decided to try to
coast on the strength of the IBM name. By the time they
started to make a decent marketing effort it was far too late.