loadavg always equal or above 1.00 - how to explain?

loadavg always equal or above 1.00 - how to explain?

[Tomasz Chmielewski]

I noticed one of my Samba + OpenLDAP servers, running 2.6.11.4 kernel 
has loadavg always equal or above 1.00, although I can't explain it.

# cat /proc/loadavg
1.00 1.10 1.06 1/65 782

This server is barely used, and as I remember, loadavg was always close 
to 0.00 on that system.

When I view the process list with top, no process takes more than 1% of 
CPU time; RAM usage is also minimal:


# free
              total       used       free     shared    buffers     cached
Mem:        320836     241016      79820          0      23308     177232
-/+ buffers/cache:      40476     280360
Swap:       811272      14612     796660

This has ~ 50 processes running (ps aux|wc -l), and ~ 50 network 
connections (netstat -tupna|wc -l), so everything normal.

Nothing unusual in dmesg, too.

What can cause this anormal load, and how can I spot it?


-- 
Tomek
http://wpkg.org
WPKG - software deployment and upgrades with Samba

Re: loadavg always equal or above 1.00 - how to explain?

[Xavier Bestel]

On Thu, 2005-12-01 at 12:57, Tomasz Chmielewski wrote:
> I noticed one of my Samba + OpenLDAP servers, running 2.6.11.4 kernel 
> has loadavg always equal or above 1.00, although I can't explain it.
[...]
> What can cause this anormal load, and how can I spot it?

Some hidden rootkit ?

	Xav

Re: loadavg always equal or above 1.00 - how to explain?

[Norbert van Nobelen]

Can you use top to determine which process is requesting most of the CPU? 


On Thursday 01 December 2005 12:57, Tomasz Chmielewski wrote:
> I noticed one of my Samba + OpenLDAP servers, running 2.6.11.4 kernel
> has loadavg always equal or above 1.00, although I can't explain it.
>
> # cat /proc/loadavg
> 1.00 1.10 1.06 1/65 782
>
> This server is barely used, and as I remember, loadavg was always close
> to 0.00 on that system.
>
> When I view the process list with top, no process takes more than 1% of
> CPU time; RAM usage is also minimal:
>
>
> # free
>               total       used       free     shared    buffers     cached
> Mem:        320836     241016      79820          0      23308     177232
> -/+ buffers/cache:      40476     280360
> Swap:       811272      14612     796660
>
> This has ~ 50 processes running (ps aux|wc -l), and ~ 50 network
> connections (netstat -tupna|wc -l), so everything normal.
>
> Nothing unusual in dmesg, too.
>
> What can cause this anormal load, and how can I spot it?

-- 
________
www.hipersonik.com : Open source experts

Re: loadavg always equal or above 1.00 - how to explain?

[Arjan van de Ven]

On Thu, 2005-12-01 at 12:57 +0100, Tomasz Chmielewski wrote:
> 
> 1.00 1.10 1.06 1/65 782
> 
> This server is barely used, and as I remember, loadavg was always
> close 
> to 0.00 on that system.

remember that load is the sum of running/runable processes and processes
in D state (waiting for IO generally, but not always). I'm pretty sure
your load comes from one of the later...

ps ought to tell you which one it is... (if not, an 
"echo t > /proc/sysrq-trigger" will dump the kernel state including the
offending process, and will also tell us where exactly that process is)

Greetings,
    Arjan van de Ven

Re: loadavg always equal or above 1.00 - how to explain?

[Tomasz Chmielewski]

Xavier Bestel schrieb:
> On Thu, 2005-12-01 at 12:57, Tomasz Chmielewski wrote:
> 
>>I noticed one of my Samba + OpenLDAP servers, running 2.6.11.4 kernel 
>>has loadavg always equal or above 1.00, although I can't explain it.
> 
> [...]
> 
>>What can cause this anormal load, and how can I spot it?
> 
> 
> Some hidden rootkit ?

highly unlikely, this machine is totally separated from the outer world, 
to break into it someone would have to break into several other servers 
first (and no problems with those).


-- 
Tomek
http://wpkg.org
WPKG - software deployment and upgrades with Samba

Re: loadavg always equal or above 1.00 - how to explain?

[Tomasz Chmielewski]

Norbert van Nobelen schrieb:
> Can you use top to determine which process is requesting most of the CPU? 

Actually, when I press shift + P in top, top is the most used process 
for a while - around 1%, then it drops to ~ 0.0-0.3% and stays like 
that; other processes (like sshd, smbd) don't take more than ~0.5% 
really few times a minute.

Same goes with memory usage.

vmstat output:

procs -----------memory---------- ---swap-- -----io---- --system-- 
----cpu----
  r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us 
sy id wa
  2  0  14612  69748  26112 184004    0    0     1     1    3     3  3 
3 94  0


iostat output:

avg-cpu:  %user   %nice    %sys %iowait   %idle
            1,79    1,52    2,66    0,33   93,70

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
hda               2,51        49,99        50,09  538412978  539475864
hdb               0,00         0,00         0,00       1744          0
fd0               0,00         0,00         0,00          6          0


-- 
Tomek
http://wpkg.org
WPKG - software deployment and upgrades with Samba

Re: loadavg always equal or above 1.00 - how to explain?

[Bernd Eckenfels]

In article <438EE515.1080001@wpkg.org> you wrote:
> What can cause this anormal load, and how can I spot it?

Look for a process in D state, might be caused by (network)filesystem
failure or a died kernel thread..

Gruss
Bernd

Re: loadavg always equal or above 1.00 - how to explain?

[Tomasz Chmielewski]

Arjan van de Ven schrieb:
> On Thu, 2005-12-01 at 12:57 +0100, Tomasz Chmielewski wrote:
> 
>>1.00 1.10 1.06 1/65 782
>>
>>This server is barely used, and as I remember, loadavg was always
>>close 
>>to 0.00 on that system.
> 
> 
> remember that load is the sum of running/runable processes and processes
> in D state (waiting for IO generally, but not always). I'm pretty sure
> your load comes from one of the later...
> 
> ps ought to tell you which one it is... (if not, an 
> "echo t > /proc/sysrq-trigger" will dump the kernel state including the
> offending process, and will also tell us where exactly that process is)

Wohoo, you're great, that was it:

root     29547  0.0  0.3   7516   996 ?        D    Nov25   0:00 CROND
root     29548  0.0  0.3   7516   996 ?        Ss   Nov25   0:00 CROND

I stopped it, and loadavg is back to 0.

Now I have to figure out what CROND was doing...

Does ps always show processes in D state in CAPITAL letters?

After cron restart it is "crond", as usual.


-- 
Tomek
http://wpkg.org
WPKG - software deployment and upgrades with Samba

Re: loadavg always equal or above 1.00 - how to explain?

[Arjan van de Ven]

> Now I have to figure out what CROND was doing...
> 
if it does it again, do that echo t > /proc/sysrq-trigger
and look for "crond" in the output, that will give a kernel backtrace of
where crond was.

> Does ps always show processes in D state in CAPITAL letters?
> 

hmm I never noticed that before, but then again "ps" may be undergoing
innovations ;)

Re: loadavg always equal or above 1.00 - how to explain?

[Zan Lynx]

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On Thu, 2005-12-01 at 14:00 +0100, Tomasz Chmielewski wrote:
[snip]
> Now I have to figure out what CROND was doing...
> 
> Does ps always show processes in D state in CAPITAL letters?
> 
> After cron restart it is "crond", as usual.

crond is the regular cron daemon.  CROND is what cron names its child
processes as they run scheduled commands.

I've seen cron stuck in D from running user crontabs on unavailable NFS
mounts.
-- 
Zan Lynx <zlynx@acm.org>

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