Messages in this thread | | | Date | Fri, 23 Jan 2009 11:19:49 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 1/2 v2] tracing/function-graph-tracer: various fixes and features |
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* Frederic Weisbecker <fweisbec@gmail.com> wrote:
> > This patch brings various bugfixes: > > _ Drop the first irrelevant task switch on the very beginning of a trace. > _ Drop the OVERHEAD word from the headers, the DURATION word is sufficient and will not > overlap other columns. > _ Make the headers fit well their respective columns whatever the selected options.
> About features, one can now disable the duration (this will hide the > overhead too for convenient reasons and because on doesn't need overhead > if it hasn't the duration
very nice! I've applied this to tip/tracing/function-graph-tracer, thanks Frederic!
this:
> I guess no one needs the nanosec precision here, the main goal is to > find when happened the events on a cpu when the trace switches from one > cpu to another. > > ie: > > 274.874760 | 1) 0.676 us | _spin_unlock(); > 274.874762 | 1) 0.609 us | native_load_sp0(); > 274.874763 | 1) 0.602 us | native_load_tls(); > 274.878739 | 0) 0.722 us | } > 274.878740 | 0) 0.714 us | native_pmd_val(); > 274.878741 | 0) 0.730 us | native_pmd_val(); > > Here there is a 4000 usecs difference when we switch the cpu.
Still needs a solution - if we do cross-CPU traces we want to have a global trace clock with 'seemless' transition between CPUs.
Ingo
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