Re: several messages

Rick Lindsley (ricklind@us.ibm.com)
Tue, 22 Apr 2003 16:38:15 -0700


Have you done any tests with a threaded process running on a single CPU in
the siblings? If they are sharing data and locks in the same cache it's
not obvious (to me at least) that it would be faster in two CPUs having to
do updates. That's a question, not an implication that it is significantly
better in just one, a threaded program with only two threads is not as
likely to be doing the same thing in both, perhaps.

True. I have a hunch (and it's only a hunch -- no hard data!) that
two threads that are sharing the same data will do better if they can
be located on a physical/sibling processor group. For workloads where
you really do have two distinct processes, or even threads but which are
operating on wholly different portions of data or code, moving them to
separate physical processors may be warranted. The key is whether the
work of one sibling is destroying the cache of another.

Rick
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/