UNIX for Advanced & Expert Users

Hi.

Allocated is showing in hexadecimal which comes to 1 GB
But the usage is showing more (14 GB). Can you please explain why? Normally, usage should be less than allocated



$ /usr/sbin/kmtune -q shmmax

Parameter Current Dyn Planned Module Version

==========================================================
shmmax 0x40000000 Y 0X40000000


$ ipcs -mba |awk '{print s+= $10}' |tail -2

1.44211e+10

1.44221e+10

What is the output of...

Code:

ipcs -mb | awk '{s+=$NF} END {print s}'

Here is the output of ipcs -mb | awk '{s+=$NF} END {print s}'

1.44221e+10

SHMMAX is not systemwide. 50 processes could each create a 1 GB shared memory segment. I'm not aware of a system-wide limit on shared memory.

Yes Perderabo is on the mark. The SHMMAX kernel tunable specifies only the maximum size of a single shared memory segment. It does not mean the total amount of shared memory that can be allocated by the OS. Googling found this SHMMAX link. The maximum amount of shared memory system-wide would be a multiple of SHMMNI * SHMMAX.