On Fri, Sep 19, 2008 at 1:22 AM, Steven Noonan <steven@xxxxxxxxxxxxxx> wrote: > On Fri, Sep 19, 2008 at 1:17 AM, Ingo Molnar <mingo@xxxxxxx> wrote: >> in tip/master there's an ftrace_printk() facility. You can just replace >> the verbose printk()s with ftrace_printk() and see the result in >> /debug/tracing/trace. >> >> This sort of tracing has very low overhead and can be used in an easy >> ad-hoc manner with no extra infrastructure. Here's a few quick-start >> links about how to enable the scheduler tracer: >> >> http://redhat.com/~mingo/sched-devel.git/readme-tracer.txt >> http://redhat.com/~mingo/sched-devel.git/howto-trace-latencies.txt >> >> any ftrace_printk() you add in the kernel will show up in that trace. >> >> (If the scheduling events are uninteresting and clutter the output then >> you might want to remove the scheduler tracing entries from kernel/*.c >> by removing the trace_sched_*() calls or use a less noisy tracer.) >> >> to get enough of a trace history you might want to increase the number >> of trace entries in /debug/tracing/trace_entries from 16K to 128K or so. >> > > Thanks for the suggestion, I'll do that. :) > It'd be extremely convenient to have a tracer that did absolutely nothing but display ftrace_printk()s. -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
