Tune Linux System Parameter

[Cliff Lim Kok Hwee]

Gd Day Forum,

I am thinking to update the following 2 parameters namely,

For semaphores,

- /proc/sys/kernel/sem

250 32000 32 128



For shared memory,

- /proc/sys/kernel/shmmax

33554432

How do I proceed?

I understand that sysctl can be used.

Is a reboot required like HP-UX post kernel tuning?

Thanks/cliff

[Muthukumar_5]

I hope system reboot is not needed at all. Just tune them with sysctl.

[Ivan Ferreira]

sysctl only changes the run time values, if you want to do permanently, you need to configure /etc/sysctl.conf, for example

sysctl -w kernel.shmmax=33554432
sysctl -w kernel.sem="250 32000 32 128"

Then add to /etc/sysctl.conf:

kernel.shmmax=33554432
kernel.sem="250 32000 32 128"

Note that the values showed use to be the default values, check the current values with

sysctl kernel.shmmax
sysctl kernel.sem

You don't need to reboot.

[Cliff Lim Kok Hwee]

Hi Forumers,

Can directly update them in the respective files works? Or must update into the /etc/sysctl.conf?

- /proc/sys/kernel/shmmax
- /proc/sys/kernel/sem

Thanks/Cliff

[dirk dierickx]

i suggest you update the config file. after that you run 'sysctl -p' to read your adjusted config file. if it works, you are _sure_ these settings will be set the next time you boot.

sysctl is an online command, so after it's run, new settings will be in use. welcome to a modern OS ;)

[Cliff Lim Kok Hwee]

Hi Forumers,

I had run the following,

sysctl -w kernel.shmmax=33554432
sysctl -w kernel.sem="250 32000 32 128"

I guess the settings will be intact upon a reboot? Cos I cannot reboot to verify. But i read in the forum the settings will be permanent upon a reboot.

Thanks/cliff

[Ivan Ferreira]

As I said before, you MUST add to /etc/sysctl.conf to make it permanent, exactly as I described.

[Steven E. Protter]

Shalom,

No reboot is usually required. Those parameters are dynamic in HP-UX v1 btw.

SEP