[pypy-dev] Helping with STM at the PyCon 2013 (Santa Clara) sprints

[Armin Rigo]

Hi Taavi,

I finally fixed pypy-stm with signals.  Now I'm getting again results
that scale with the number of processors.

Note that it stops scaling up at some point, around 4 or 6 threads, on
machines I tried it on.  I suspect it's related to the fact that
physical processors have 4 or 6 cores internally, but the results are
still a bit inconsistent.  Using the "taskset" command to force the
threads to run on particular physical sockets seems to help a little
bit with some numbers.  Fwiw, I got the maximum throughput on a
24-cores machine by really running 24 threads, but that seems
wasteful, as it is only 25% better than running 6 threads on one
physical socket.

The next step will be trying to reduce the overhead, currently
considerable (about 10x slower than CPython, too much to ever have any
net benefit).  Also high on the list is fixing the constant memory
leak (i.e. implementing major garbage collection steps).


A bientôt,

Armin.