This is a tiny Perl module to read CPU topology information from sysfs.
Interpreting this topology is useful when you want to control on which hardware threads you want your software threads to run, e.g. when running latency-sensitive code.
Inspect list.pl to see how the perl module can be used.
The script has use of its own, when paired with taskset(1). For example,
on a machine with 4 sockets and 8 2-way cores per socket, i.e. a total
of 64 threads:
$ ./list.pl --policy=scatter 16
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
, i.e. four threads per socket.
$ ./list.pl --policy=compact 16
0,4,8,12,16,20,24,28,1,5,9,13,17,21,25,29
, i.e. eight threads per socket, using two sockets.
$ ./list.pl --policy=compact-smt 16
0,4,8,12,16,20,24,28,32,36,40,44,48,52,56,60
, i.e. all threads in the same socket, leveraging SMT.
- Only the topology (socket->core->thread) is read; all other information (e.g. cache sizes) is ignored. There exist other (more complex) packages for this.
- Linux, with sysfs mounted on /sys
Public domain via CC0 -- see LICENSE.
Emilio G. Cota cota@braap.org