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max size of shared memory

hello every body,
how do I know what the upper limit is on my server for my shared
memory
> settings?
is there anyperson knowing about this please explain?

Have a look in your source tree for tmpfs.txt
Default is half of your RAM (not including swap) - can be increased, but heed the warning.

From a sybase pdf:

Quote:

The operating system shared memory default of most Linux releases is
32MB. The minimum required by Adaptive Server is 64MB for a default
Server with 2K pages. You must increase the amount of shared memory if
you plan to increase the total memory of Adaptive Server.
Use the sysctl(8) method to check and adjust the operating system shared
memory parameter.
• To check the current shared memory size, enter:
# /sbin/sysctl kernel.shmmax
• To adjust the shared memory size, enter the following, where nnn is
the new size in bytes (at least 64MB which is 67108864 bytes):
# /sbin/sysctl -w kernel.shmmax=nnn
To guarantee that this value is applied every time the system is started,
add this line to your /etc/rc.d/rc.local file (/etc/init.d/boot.local on
SuSE systems).

Look in /proc as well. There may be a SC_SHMMAX or _XVID_SSHMAX using sysconf but I can't check now. My linux machine is at home.

Wellll - yes and no.
That's actually the segment size, not the max shared memory that could (potentially) be allocated.

Depends on what's needed in the particular case I guess.

I had just checked on SHMMAX and realized that it was for indivual segment limits. You responded before I could alter my post.

Code:

KERN_SHMMAX=34, /* long: Maximum shared memory segment */

thanks a lot for all.

Quote:

Originally Posted by jschiwal

From a sybase pdf:

Look in /proc as well. There may be a SC_SHMMAX or _XVID_SSHMAX using sysconf but I can't check now. My linux machine is at home.

sir,
thanks a lot for ur reply it works out well.i need one more clarification sir, how much max of shared memory shall we give for server? is there any limit ? and what do you mean by adaptive server?