MTsort Shared Memory Spectra

Shared Memory Spectra

From release version 4.5 spectra are contained in POSIX shared memory as opposed to Unix shared memory segments as previously.

This appears as a single "file" per sort in the /dev/shm directory.
The shared memory space in Linux is allocated as a TMPFS filesystem, which by default, is allocated half of the system RAM space.
This space can safely be increased (upto e.g. RAMsize - 50MB) by
a) edit /etc/fstab and add (e.g. for 500MBytes) size=500m option to /dev/shm line
b) Debian: edit /etc/default/tmpfs, and add value to TMPFS_SIZE=

These objects are allocated dynamically to the process virtual address space, and hence, in principle, more space can be allocated than before.
There is now no inbuilt limit in the sort package.

Sort Local Data Space

within this space are allocated maps, arrays and variables used by the sort program.
This is now allocated in a similar way to spectra, and again, there is now no inbuilt limit on space.

Maintained by Janet Sampson and John Cresswell (University of Liverpool)
Email to support@ns.ph.liv.ac.uk