Re: [PATCH for tip] ftrace: remove latency_trace document

Ingo Molnar
2009-03-08T15:42:19Z

* KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

> 2009/3/8 Frederic Weisbecker <fweisbec@gmail.com>:
> > On Sat, Mar 07, 2009 at 11:53:40PM +0900, KOSAKI Motohiro wrote:
> >> Subject: [PATCH] remove latency_trace document
> >>
> >> Currently, there aren't "Latency tracer" and latency_trace file.
> >> Then, its documentation is removed too.
> >
> > Hi,
> >
> > The latency_trace file has been removed but the latency tracing stil exists.
> > It has become an option instead of a file now:
> >
> > echo latency-format > /debugfs/tracing/trace_options
> >
> > There are even some tracers that default enable it (irqsoff, preemptoff...)
> > IMO, the documentation about latency tracing shouldn't be removed but
> > just updated a bit to reflect this change.
>
> Ah, sorry.
> I totally misunderstood it.
>
> thanks to correct my fault.

You are correct to point out that the documentation about
latency tracing does need to be updated - as there's no
latency_trace file anymore and we reference it in a few places:

Documentation/ftrace.txt: latency_trace:
Documentation/ftrace.txt: is retrieved. Unlike the "trace" and "latency_trace"
Documentation/ftrace.txt: "latency_trace" files are static, and if the
Documentation/ftrace.txt: "trace" or "latency_trace". A new max trace will
Documentation/ftrace.txt: trace via the latency_trace file.
Documentation/ftrace.txt:For traces that display latency times, the latency_trace file
Documentation/ftrace.txt: latency_trace file is relative to the start of the trace.
Documentation/ftrace.txt: verbose - This deals with the latency_trace file.
Documentation/ftrace.txt: trace,trace_pipe,latency_trace. Example:
Documentation/ftrace.txt: # cat /debug/tracing/latency_trace
Documentation/ftrace.txt: # cat /debug/tracing/latency_trace
Documentation/ftrace.txt: # cat /debug/tracing/latency_trace
Documentation/ftrace.txt: # cat /debug/tracing/latency_trace

Ingo