Very Computer

The issue appears to be with memory usage. Whenever I try to do something
big and slow and memory-intensive (such as start up Mozilla or compile the
Glasgow Haskell Compiler, to recall from recent memory), the poor thing
starts thrashing very badly. From another shell, I then check what "free"
tells me,
and it reports that, indeed, the system is very short on memory - but, in
fact, well over half the available memory is taken up by buffers and cache
(?!).

Is this typical? It seems awful wasteful to me, not to mention futile - a
disk cache large enough to induce thrashing would seem to defeat its own
purpose. Do I just have too darned little RAM, or is there something I can
tweak? (I swear, on that other machine I can surf the Web and compile the
kernel while an MP3 plays at good quality without skipping; on my box, just
surfing the Web brings everything down.)

Jyrinx
jyrinx_list at mindspring dot com

P.S. This newsgroup is rather busy ... is there a more specific group for
this question? Perhaps someone (with more time/expertise/equipment than me)
should start a comp.os.linux.kernel ...

Quote:> and it reports that, indeed, the system is very short on memory - but, in
> fact, well over half the available memory is taken up by buffers and cache
> (?!).

> Is this typical? It seems awful wasteful to me, not to mention futile - a
> disk cache large enough to induce thrashing would seem to defeat its own

Otherwise, you should use 2.4.10+ (2.4.13 is latest) LT-series kernel
which implements an improved 2.2 VM subsystem versus the Riel VM
subsystem introduced with 2.4.

--

Software Developer, Engineering Services
Red Hat, Inc.

QUIPd 0.20: (61 of 531)
-> If you are going to sin, sin against God, not the bureaucracy. God
-> will forgive you but the bureaucracy won't.
-> - Hyman Rickover

I'll try getting the newest kernel. Thanks for your help!

Jyrinx
jyrinx_list at mindspring dot com

I'm still running the same computer I was running more than five years ago.
It's just had all of its guts (and its casing) replaced ... a few times. ;>

--

:> and it reports that, indeed, the system is very short on memory - but, in
:> fact, well over half the available memory is taken up by buffers and cache
:> (?!).
:>
:> Is this typical? It seems awful wasteful to me, not to mention futile - a
:> disk cache large enough to induce thrashing would seem to defeat its own
:
:It's extremely useful on machine with much memory. And as such, in your
:case - I'd recommend biting the bullet and buy more memory (since it's
:_SO_ cheap).

Mmmm... in a machine of that age, the memory is not likely to be as
cheap as the newer memory sticks are.
Mats Wichmann

It's quite typical for a system that has been running for a while to
have _no_ unused memory; memory that's not being used for _anything_
is just sitting there consuming electricity.  If there's RAM in use as
cache, then obviously the system _does_ have enough memory for what
it's being used for, because the system will throw cache away before
it allocates swap space.

The only way you're likely to have both (memory free|used as cache)
and (swap consumed) is if some program wound up consuming enough RAM
to fill memory (reducing cache to 0), and swapped part of either
data/program out to swap space.  Subsequently, other memory got
deallocated, and since the swapped-out data has never been pulled in,
it just gets left there...

Long and short:

  It's normal _and good_ for the amount of free memory to get drawn to
  zero by using it to cache disk accesses.
--

http://www.ntlug.org/~cbbrowne/unix.html
"Laugh-a while you can, Monkey Boy."  -- Dr. Lizardo - Buckaroo Banzai