According to the rhel document, the total amount of shared memory available on the system equals to shmall*PAGE_SIZE. After I completed the installation of RHEL6, the value of the shmall kernel parameter defaults to 4294967296，which means that the total amount of shared memory pages that can be used system wide is 4294967296, and the page size is 4096B. So, based on the formula, the size of shared memory is
which is much more than the size of RAM(8GB) the operating system has.How an os can find 16TB shared memory to allocate?
So, is the size of
/dev/shm actually equal to the size of shared memory? If not, how can I get the actual size of shared memory?