Oracle and shmmax and shmall

A good article on Oracle and shmmax and shmall. In a nutshell:

• shmall it is not the maximum amount of memory which can be allocated, it is the maximum size of any shared memory chunk – how big a bite you want per bite from free memory.
• shmmax – its value determines the maximum amount of memory that ALL shared memory can take. the actual setting is derived… the maximum amount of memory = shmall * pagesize where pagesize = getconf PAGE_SIZE and shmall = cat /proc/sys/kernel/shmall