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From: Frederic Weisbecker on 15 Apr 2010 16:00
On Wed, Apr 14, 2010 at 09:50:52AM +0200, Jiri Olsa wrote:
> On Tue, Apr 13, 2010 at 01:33:37AM +0200, Frederic Weisbecker wrote:
> > On Fri, Apr 02, 2010 at 07:01:22PM +0200, Jiri Olsa wrote:
> > > +#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
> > > + TRACE_GRAPH_PRINT_PROC)
> > > +
> > > +static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
> > > +{
> > > + u32 flags = GRAPH_TRACER_FLAGS;
> > > +
> > > + if (trace_flags & TRACE_ITER_LATENCY_FMT)
> > > + flags |= TRACE_GRAPH_PRINT_DURATION;
> > > + else
> > > + flags |= TRACE_GRAPH_PRINT_ABS_TIME;
> >
> >
> >
> > Why not having ABS_TIME in any case?
> >
> > And more important, you probably want to add TRACE_ITER_LATENCY_FMT
> > as well to get the contexts (need-resched, hardirq/softirq, preempt-depth,
> > lock-depth)
>
> hi,
>
> latency info
> The latency info is governed by global 'trace_flags', the graph tracers
> follows that as well.
>


Doh, right.



> absolute time
> The idea was to follow the current irqsoff function trace format. Though
> it cannot be exatly the same, it can print the same info.
>
> By default I added TRACE_GRAPH_PRINT_CPU and TRACE_GRAPH_PRINT_PROC,
> since they are always there for current irqsoff trace.
>
> Then the absolute time is printed only in the case when the
> latency info is switched off.
>
> AFAICS the 'time' field in the output (for latency enabled) actually
> represents the duration (computed/printed in trace_print_lat_context function).
> Hence I added TRACE_GRAPH_PRINT_DURATION to graph output for the latency case.
>
> So the answer to your question is, the absolute time is not part
> of the output, since it's not part of the original trace output.
> My opinion is the absolute time is not be that important
> for this tracer, the duration is.



I agree, I've actually made a confusion between both :)



>
>
> latency output OFF:
>
> current tracer:
> TASK-PID CPU# TIMESTAMP FUNCTION
>
>
> graph tracer:
> TIME CPU TASK/PID FUNCTION CALLS
>
>
> latency output ON:
>
> current tracer:
> _------=> CPU#
> / _-----=> irqs-off
> | / _----=> need-resched
> || / _---=> hardirq/softirq
> ||| / _--=> preempt-depth
> |||| /_--=> lock-depth
> |||||/ delay
> cmd pid |||||| time | caller
> \\ / |||||| \\ | /
>
>
>
> graph tracer:
> _-----=> irqs-off
> / _----=> need-resched
> | / _---=> hardirq/softirq
> || / _--=> preempt-depth
> ||| / _-=> lock-depth
> |||| /
> CPU TASK/PID ||||| DURATION FUNCTION CALLS
>
>
> Also the non-latency case covers the 'verbose' option output.
>
>
>
>
> thanks for your comments,
> hopefully I haven't missed anything.. ;)



And thanks for your work!

For me it's ok.

Acked-by: Frederic Weisbecker <fweisbec(a)gmail.com>

Steve?

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