On 12/22/06, Matthew Jarvis <[EMAIL PROTECTED]> wrote:
total used free shared buffers cached
Mem: 1511 1490 21 0 134 1039
-/+ buffers/cache: 315 1195
Swap: 1027 100 926
<snip>
Any advice on this?
By these numbers I'd say you have plenty of RAM. of your 1.5GB, 1 GB
is being used by cache, which in most cases is disk cache. The Linux
VMM is (in most cases) set to be very aggressive with cache usage, so
even though your memory looks "full", a substantial portion of that
cache can be freed for program execution should it be needed.
For example, on my workstation right now I get:
[EMAIL PROTECTED]:~$ free -m
total used free shared buffers cached
Mem: 3821 3796 24 0 53 2891
-/+ buffers/cache: 850 2970
Swap: 7216 72 7144
After opening OpenOffice:
[EMAIL PROTECTED]:~$ free -m
total used free shared buffers cached
Mem: 3821 3775 46 0 55 2844
-/+ buffers/cache: 875 2945
Swap: 7216 72 7144
Notice that even though "effectively all" of my RAM was "in use"
before I started OOo, afterwards the swap values have not changed.
That's because the VMM has scavenged space from the cached RAM for
OOo.
The only time to be concerned about swap usage, especially on
long-running machines is if the swap values are getting large _and_
you have little or nothing in buffers or cache.
Again, based on the numbers you provided, I'd say RAM is not a problem
for this machine. If this machine is having performance problems, it's
more likely an IO or CPU bottleneck.
To get a quick high level view of CPU use, look at the load average in
top. That number is the number of processes that are currently queued
waiting for CPUtime. In most cases, if this number is larger than the
number of CPU's you have the machine would benefit from more cpu
power, either in the form of more cores or more Mhz. There are some
exceptions to this (like busy sendmail boxes) but that's a good rule
of thumb.
For io, use iostat and look at the %iowait. That is the percentage of
processes that are having to wait on an io operation to do their work.
if this number gets and stays "high", like over 50% or so, I'd say you
need a faster storage subsystem.
--
-Regards-
-Quentin Hartman-
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