On Mon, Mar 03, 2014 at 07:41:17PM +0100, Peter Zijlstra wrote: > On Mon, Mar 03, 2014 at 01:07:00PM -0500, Joe Mario wrote: > > If you only sample on the HITMs then you don't get the store misses. > > That means you'll not be able to detect who is simultaneously tugging > > on the same cache lines. That gives up much of the value of "perf > > c2c". > > As long as you know which lines are hurting bringing in (loads) you can > often figure out who is doing the stores on them.
Yes, especially since every store is a load too (unless you're talking WC) The method c2c uses is more exact, but keep in mind it's a sampling heuristic in any cases, with some potential bias. load-latency tags the loads randomly and there's no guarantee that tagging is fully uniform. Also you only see a subset in any case. > > > As we developed this, we ended up settling on Ivy Bridge to get the > > behavior we wanted. > > Wouldn't SNB also work? Yes. Haswell is best however because it can report addresses on far more events. -Andi -- [email protected] -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
