On Fri, 21 Aug 2015 15:45:58 -0500 Isaac Griswold-Steiner <isaac.griswold.steiner@xxxxxxxxx> wrote: > From: Isaac Griswold-Steiner <isaac.griswoldsteiner@xxxxxx> > > rdtscbench is a cyclictest-like tool that spawns a thread per cpu. Each thread > measures the difference in cycle count (using the tsc) during the execution of a > tight loop. > > This is a simple tool intended to be used for the validation of nohz_full CPU > configurations. As the validation of nohz_full CPUs is the objective, the tool > avoids the usage of system calls, timers, or anything that might break nohz_full. > Isaac, A question and a request. Was there any particular reason you used sleep() rather than clock_nanosleep() in your cycles_per_second function? I see that you did ten samples but wondered if the slop from a HZ-based wakeup might still introduce some error, as opposed to a more precise programmed wakeup. Also, I'd appreciate it if you would expand a bit on the usage section in your README file, specifically how you tune a system prior to running rdtscbench, what output indicates that your tuning is *not* working, versus when to know you're doing the right things. It's probably as simple as saying "if the max latency numbers are spiking you have a problem" but it's good to be explicit about that sort of thing. Thanks, Clark -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
