kernel.shmmax does nothing if you don't bump up kernel.shmall
accordingly but I can tell you the cap is something wrong with your
application not the OS.
at one time I supported an application that in normal operation used
64BG Resident memory per instance.
And currently my PostgreSQL servers often spike to as much as 2GB of
ram per connection and would use more if i didn't cap it there in the
configurations.

I don't think the kernel settings are your problem what language is
the application written in?
Is it executed by an other process like Apache or Tomcat for example?


On Wed, Mar 27, 2013 at 11:09 PM, Duke Nguyen <[log in to unmask]> wrote:
> On 3/27/13 11:52 PM, Attilio De Falco wrote:
>>
>> Just a stab in the dark, but did you check the Shared Memory kernel
>> parameter (shmmax), type "cat /proc/sys/kernel/shmmax".  We have it set very
>> high so that any process/thread can use as much memory as it needs.  You set
>> the limit to 1 GB without rebooting by typing "echo 1073741824 >
>> /proc/sys/kernel/shmmax"  or modify /etc/sysctl.conf and add the line
>> "kernel.shmmax = 1073741824" so remains after a reboot.  I'm not sure about
>> abinit but some fortran programs need shmmax limit to be set high…
>
>
> Hi Attilio, we already had it at very high value (not sure why, I never
> changed/edited this value before)
>
> [root@biobos:~]# sysctl -p
> net.ipv4.ip_forward = 1
> net.ipv4.conf.default.rp_filter = 1
> net.ipv4.conf.default.accept_source_route = 0
> kernel.sysrq = 0
> kernel.core_uses_pid = 1
> net.ipv4.tcp_syncookies = 1
> error: "net.bridge.bridge-nf-call-ip6tables" is an unknown key
> error: "net.bridge.bridge-nf-call-iptables" is an unknown key
> error: "net.bridge.bridge-nf-call-arptables" is an unknown key
> kernel.msgmnb = 65536
> kernel.msgmax = 65536
> kernel.shmmax = 68719476736
> kernel.shmall = 4294967296
> [root@biobos:~]# cat /proc/sys/kernel/shmmax
> 68719476736
>
> Any other suggestions?
>
>
>>
>> On Mar 26, 2013, at 9:59 PM, Duke Nguyen <[log in to unmask]> wrote:
>>
>>> Hi folks,
>>>
>>> We have SL6.3 64bit installed on a box with two quad core and 8GB RAM. We
>>> installed openmpi, Intel Studio XE and abinit to run parallel (8
>>> cores/processes) some of our applications. To our surprise, the system
>>> usually takes only about half of available memory (about 500MB each core)
>>> and then the job/task was killed with the low-resource error.
>>>
>>> We dont really understand why there is a cap of "512MB" (I guess it would
>>> be 512MB instead of 500MB) for each of our cores whereas in theory, each of
>>> the core should be able to run up to 1GB. Any
>>> suggestions/comments/experience about this issue?
>>>
>>> Thanks in advance,
>>>
>>> D.
>>>
>