Re: [PATCH 4/5] tracing/fastboot: Add a time field on the sched_switchentry

From: Tim Bird
Date: Fri Oct 17 2008 - 19:30:06 EST

ï wrote:
> 2008/10/12 Frïdïric Weisbecker <fweisbec@xxxxxxxxx>:
>> 2008/10/12 Steven Rostedt <rostedt@xxxxxxxxxxx>:
>>> You can tap into the context switch trace_point too, and have that record
>>> a special trace entry for you instead.
> Another thing I could do: when a sched switch entry occurs, I could
> send a special timestamp entry that
> fits my needs just before the commit of the sched entry, only if the
> current tracer is the boot tracer. This way I can output
> the appropriate timestamp just before output the sched entry.
> What do you think?

I may have lost context here, but what's the purpose of the
extra timestamp again? If it's just to have zero-based
timestamps on the ultimate output, can't you just put a single
special "start" timestamp in the trace log. Then that can
be subtraced from all tracer-generated stamps in post-processing.
I'm not familiar enough with the tracer to know if the
post-processing is done in kernel space. But in any event
you could use something like scripts/show_delta to get
relative timestamps (in user space). Right now, scripts/show_delta
doesn't act like a filter - I'll have to look at that.

Sorry if I'm just adding noise...
-- Tim

Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Corporation of America

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at