On Wed, May 23, 2007 at 12:33:11PM +0200, Ingo Molnar wrote: > * Peter Zijlstra <[EMAIL PROTECTED]> wrote: ... > > It also measures lock wait-time and hold-time in nanoseconds. The > > minimum and maximum times are tracked, as well as a total (which > > together with the number of event can give the avg). > > > > All statistics are done per lock class, per write (exclusive state) > > and per read (shared state). > > > > The statistics are collected per-cpu, so that the collection overhead > > is minimized via having no global cachemisses. ... > really nice changes! The wait-time and hold-time changes should make it > as capable as lockmeter and more: lockmeter only measured spinlocks, > while your approach covers all lock types (spinlocks, rwlocks and > mutexes). > > The performance enhancements in -v2 should make it much more scalable > than your first version was. (in fact i think it should be completely > scalable as the statistics counters are all per-cpu, so there should be > no cacheline bouncing at all from this)
per cpu is pretty important since you can potentially hit that logic more often with your wait-time code. You don't want to effect the actual measurement with the measurement code. It's that uncertainty principal thing. It is looking pretty good. :) You might like to pretty the output even more, but it's pretty usable as is. bill - 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/
