Difference between dynamic and static kernel parameters?

[sudhapage]

Hi all,

What is the difference between static and dynamic kernel parameters?

Regards,
Sudhakaran.K

[Steven E. Protter · Accepted solution]

Shalom,

dynamic can be changed on the fly without booting the system. The kmtune command (11.11) and kctune on 11.23 will let you do this.

Static parameters can not be changed without first compiling a new kernel and booting the system.

SEP

[sysadm_1]

Dynamic Kernel Parameters:You can change them, they take effect immediately, and you don't have to reboot the machine.

Static kernel parameters :You have to modify the parameter, generate a new kernel and reboot the machine before the value will take effect.

[inventsekar_1]

Hi Sudhakaran,
so,u found the difference between static and dynamic.

how i understood is:(it may be false. i simply use this for understanding)
Static parameters means, they are read only variables. we can change it before rebooting only.
static parameters affects important system services. so when we change them to tell the new value to the running services and process, we need to stop all the services and restart it. think it as system reboot.

dynamic parameters means, they are read and write variables. we can change it.


for 11.23,
Currently, the following tunables are dynamic:

maxuprc - maximum number of user processes

msgmax - message maximum size in bytes

msgmnb - maximum number of bytes on a message queue

shmmax - maximum shared memory segment size in bytes

shmseg - shared memory segments per process

maxtsiz - maximum text segment size in bytes for 32-bit programs

maxtsiz_64bit- maximum text segment size in bytes for 64-bit programs

maxfiles_lim - hard file limit per process

core_addshmem_read - include readable shared memory in process core dump

core_addshmem_write - include writable shared memory in process core dump

http://docs.hp.com/en/5187-0172/ch10s07.html

refer kmtune and kctune(11.23) man pages also

[Tim Nelson]

Don't forget that if you do not build the dynamic values into the kernel they will reset back to what they were after reboot.

Also keep in mind that some applications do not like to have their parameters changed while they are running. I do not know of any in particular but better to be safe than sorry.