Nowadays PC server can be installed with large amount of physical memory,
but QNX is limited to 4 GB of VIRTUAL MEMORY which is a big problem if we
have processes sharing the same huge data space (shmem). For example, if we
have 1 GB of physical memory, and if our process code size is 2 MB sharing
the same data space of total size 200MB, then we can only run AT MOST 19
processes of the same program. At first we thought we could run over 100
processes because the shmem would occupy 200MB of the physical memory and
the 100 processes would occupy 2MB of the physical memory because they use
the same code space. It is true in term of physical memory, but not in
VIRTUAL MEMORY. Each process uses the same physical memory area for the
200MB shared memory, therefore adding new process does not increase the
physical memory usage at all. But each process occupies 200MB of virtual
memory (with different virtual address), which runs out of space when we run
our 20th process.
Does anyone know how to solve this constraint?
Regards,
Johannes