high memory usage on Linux host

high memory usage on Linux host

[askzaman askzaman]

In one of  Linux host , sar is showing always high memory usage .
looks like some little amount of swapping also ( %swpused ) but free
is not reporting any swapping.

=====
12:00:01 AM kbmemfree kbmemused  %memused kbbuffers  kbcached
kbswpfree kbswpused  %swpused  kbswpcad

08:40:01 AM    224796   7944056            97.25    178364
5898568   8121928       432              0.01       432
08:50:01 AM    224724   7944128            97.25    178364
5898500   8121928       432              0.01       432
09:00:01 AM    224572   7944280            97.25    178364
5898500   8121928       432              0.01       432
Average:          227441   7941411             97.22    178339
5898181   8121928       432               0.01       432
------
-bash-3.00$ free -m
             total       used       free     shared    buffers     cached
Mem:          7977       7752        224          0        174       5760
-/+ buffers/cache:       1818       6159
Swap:         7931          0       7931
=====


The host has apache , java  running and one our custom application .
But these applications are just running  and are not serving any
traffic .

====
Tasks: 221 total,   1 running, 220 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.2% us,  0.1% sy,  0.0% ni, 99.2% id,  0.0% wa,  0.0% hi,  0.5% si
Mem:   8168852k total,  7942712k used,   226140k free,   178372k buffers
Swap:  8122360k total,      432k used,  8121928k free,  5898628k cached

  PID USER      PR  NI %CPU    TIME+  %MEM  VIRT  RES  SHR S COMMAND
19657 nobody    16   0    0   1:30.18  1.5  719m 122m 9.9m S
java_daemon
 6545  nobody     15   0    1 198:18.07  1.0  527m  83m 5508 S
tcs_server
15732 nobody    16   0    0   2:23.94  0.2 31964  18m 5008 S    apache
15716 nobody    16   0    0   2:08.11  0.2 32016  18m 4952 S    apache
15733 nobody    16   0    0   2:09.58  0.2 31980  18m 4944 S    apache
15718 nobody    16   0    0   2:27.99  0.2 31976  18m 4936 S    apache
15735 nobody    16   0    0   2:28.53  0.2 31952  18m 4952 S    apache
15738 nobody    16   0    0   2:39.02  0.2 31952  18m 4928 S    apache
15727 nobody    16   0    0   2:16.02  0.2 31948  18m 4920 S    apache
15725 nobody    16   0    0   2:28.89  0.2 32024  18m 4928 S    apache
15724 nobody    16   0    0   2:25.61  0.2 31856  18m 4944 S    apache
 7076 nobody    16   0    0   2:01.68  0.2 31400  18m 4912 S
apache
 7091 nobody    16   0    0   2:03.89  0.2 31316  17m 4936 S
apache
====


The above out is in terms of high memory usage.

Can somebody explain why sar is reporting high memory usage on host .


The OS is RHEL 4 .


Any help will be highly appreciated.

Re: high memory usage on Linux host

[Michael Wünsch]

> The host has apache , java  running and one our custom application .
> But these applications are just running  and are not serving any
> traffic .
Have you looked into your -Xms or similar options for Java? If you are
giving it a high initial value, it will not drop below that. Also what
do you perceive as high memory usage? 77% of your memory are free
(subtracting the caches).

Regards,
--
Michael Wünsch
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Re: high memory usage on Linux host

[Nicolas Maupu]

Hi,

I presume SAR does not substract buffers and caches memory to compute
percentage ...

Regards,
Nicolas Maupu

On Mon, Nov 8, 2010 at 10:43, Michael Wünsch <Liganic@gmx.net> wrote:
>
> > The host has apache , java  running and one our custom application .
> > But these applications are just running  and are not serving any
> > traffic .
> Have you looked into your -Xms or similar options for Java? If you are
> giving it a high initial value, it will not drop below that. Also what
> do you perceive as high memory usage? 77% of your memory are free
> (subtracting the caches).
>
> Regards,
> --
> Michael Wünsch
> --
> To unsubscribe from this list: send the line "unsubscribe linux-admin" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html



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