On Tue, 2007-05-29 at 13:28 -0700, Daniel Walker wrote: > On Tue, 2007-05-29 at 14:52 +0200, Peter Zijlstra wrote: > > + now = sched_clock(); > > + waittime = now - hlock->waittime_stamp; > > + > > It looks like your using sched_clock() through out .. It's a little > troubling considering the constraints on the function .. Most > architecture implement a jiffies sched_clock() w/ 1 millisecond or worse > resolution.. I'd imagine a millisecond hold time is pretty rare, even a > millisecond wait time might be fairly rare too .. There's also no > guarantee that sched_clock timestamps off two different cpu's can be > compared (or at least that's my understanding) ..
All valid points, however.. calling anything more expensive 2-3 times per lock acquisition is going to be _very_ painful. Also, IMHO the contention count vs the acquisition count is the most interesting number, the times are just a nice bonus (if and when they work). - 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/
