Setting kernel.shmmax 1

[zum]

Hi,

I'm running Fedora 3 and I'm having a problem when I change my kernel.shmmax setting to stay saved after I reboot.

To change it I do this command:

/sbin/sysctl -w kernel.shmmax=

What else needs to be done to keep this change in effect after I reboot?

Thanks,

zum

 

[Deleted]

More likely this kernel.shmmax is a parameter that needs to be set when compiling linux.

Look for the sysctl.conf and loader.conf.

You can add your parameters there..

Example for FreeBSD /etc/sysctl.conf

kern.maxfiles=1000000           # System-wide limit
kern.maxfilesperproc=1000000    # Per-process limit
kern.ipc.somaxconn=1000000      # Socket limit
kern.maxprocperuid=1000000      # Process per uid
kern.maxfilesperproc=1000000    # File per process

and..

Example for FreeBSD /boot/loader.conf

kern.maxusers="1000"            # Compile time parameter

The difference between OS's is minor.. man sysctl and loader to check for syntax differences.

http://unixjunky.com

 

[KissArmy]

After you run /sbin/sysctl....
what is the value in /proc/sys/kernel/shmmax? After rebooting, what is it? In the past, on other Linuxes, I usually just go to /proc/sys/kernel and: echo value > shmmax.

 

[zum]

KissArmy,

Thanks, I did what you suggested and it works.

Unixjunky,

Are those the settings you change with your FreeBSD server?
Why do you set your maxusers so high? Does it give you better performance?

 

[Deleted]

Prevents a local denial of service when the max connections have been met. I run several FreeBSD racks that serve pages and scripts to over 200,000 users. In the case when you can't recompile the kernel this method works great.

http://unixjunky.com

 

[zum]

Wow. Do you ever have any performance issues with that many users? We have about 6 FreeBSD servers but only have 30 users. I always wondered how well FreeBSD would handle performance wise with a lot of users.

 

[Deleted]

Nope.. depends on the programming environment used when building .cgi's. My servers run Apache and all scripts run under the Mod_Perl environment. Built for speed..

http://unixjunky.com