On Thu, 2007-10-25 at 13:23 -0400, Steven Rostedt wrote: > > Please don't top post. > > -- > > On Thu, 25 Oct 2007, Jaswinder Singh wrote: > > > Hello Daniel and Sven-Thorsten Dietrich, > > > > Can you please let me know the procedure of : > > 1. high resolution timers from userspace > > http://rt.wiki.kernel.org/index.php/Cyclictest > > > 2. ingo's irq latency timing and tracing > > I need to write up some howtos for that. > > > > > I will also try these methods and try to compare the performance numbers. > > > > The cyclictest is fine for comparisons, but the latency trace is only > available with the -rt patch. > First, configure IRQ timing or wake-up timing in Kernel Hacking. IRQ-disabled, and preempt-disabled Kernel code-paths are measured. If you enable latency tracing, code paths are reported to /proc/latency_trace if they exceed the cpu-cyles-count specified in proc/sys/kernel/preempt_thresh. If you enable histogram, you get the distribution. To enable latency tracing, use the following commands: # cd /proc/sys/kernel # echo 400000 > preempt_thresh # echo 1 > trace_enabled # echo 0 > preempt_max_latency You need to set preempt_thresh to a reasonably large cycles value, or you will get traces for every Kernel transition. Sven > -- Steve > - 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
