tracing: Remove mentioning of legacy latency_trace file from documentation

[~andy/linux] / Documentation / trace / ftrace.txt

diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index a39b3c749de58c12129d80d0ffad738f9a7836f0..355d0f1f8c501ebf244f71fd45a777e7ee26649c 100644 (file)
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -85,26 +85,19 @@ of ftrace. Here is a list of some of the key files:
        This file holds the output of the trace in a human
        readable format (described below).
 
        This file holds the output of the trace in a human
        readable format (described below).
 

-  latency_trace:
-
-       This file shows the same trace but the information
-       is organized more to display possible latencies
-       in the system (described below).
-

   trace_pipe:
 
        The output is the same as the "trace" file but this
        file is meant to be streamed with live tracing.
   trace_pipe:
 
        The output is the same as the "trace" file but this
        file is meant to be streamed with live tracing.

-       Reads from this file will block until new data
-       is retrieved. Unlike the "trace" and "latency_trace"
-       files, this file is a consumer. This means reading
-       from this file causes sequential reads to display
-       more current data. Once data is read from this
-       file, it is consumed, and will not be read
-       again with a sequential read. The "trace" and
-       "latency_trace" files are static, and if the
-       tracer is not adding more data, they will display
-       the same information every time they are read.
+       Reads from this file will block until new data is
+       retrieved.  Unlike the "trace" file, this file is a
+       consumer. This means reading from this file causes
+       sequential reads to display more current data. Once
+       data is read from this file, it is consumed, and
+       will not be read again with a sequential read. The
+       "trace" file is static, and if the tracer is not
+       adding more data,they will display the same
+       information every time they are read.

 
   trace_options:
 
 
   trace_options:
 


@@ -117,10 +110,10 @@ of ftrace. Here is a list of some of the key files:
        Some of the tracers record the max latency.
        For example, the time interrupts are disabled.
        This time is saved in this file. The max trace
        Some of the tracers record the max latency.
        For example, the time interrupts are disabled.
        This time is saved in this file. The max trace

-       will also be stored, and displayed by either
-       "trace" or "latency_trace".  A new max trace will
-       only be recorded if the latency is greater than
-       the value in this file. (in microseconds)
+       will also be stored, and displayed by "trace".
+       A new max trace will only be recorded if the
+       latency is greater than the value in this
+       file. (in microseconds)

 
   buffer_size_kb:
 
 
   buffer_size_kb:
 


@@ -210,7 +203,7 @@ Here is the list of current tracers that may be configured.
        the trace with the longest max latency.
        See tracing_max_latency. When a new max is recorded,
        it replaces the old trace. It is best to view this
        the trace with the longest max latency.
        See tracing_max_latency. When a new max is recorded,
        it replaces the old trace. It is best to view this

-       trace via the latency_trace file.
+       trace with the latency-format option enabled.

 
   "preemptoff"
 
 
   "preemptoff"
 


@@ -307,8 +300,8 @@ the lowest priority thread (pid 0).
 Latency trace format
 --------------------
 
 Latency trace format
 --------------------
 

-For traces that display latency times, the latency_trace file
-gives somewhat more information to see why a latency happened.
+When the latency-format option is enabled, the trace file gives
+somewhat more information to see why a latency happened.

 Here is a typical trace.
 
 # tracer: irqsoff
 Here is a typical trace.
 
 # tracer: irqsoff


@@ -380,9 +373,10 @@ explains which is which.
 
 The above is mostly meaningful for kernel developers.
 
 
 The above is mostly meaningful for kernel developers.
 

-  time: This differs from the trace file output. The trace file output
-       includes an absolute timestamp. The timestamp used by the
-       latency_trace file is relative to the start of the trace.
+  time: When the latency-format option is enabled, the trace file
+       output includes a timestamp relative to the start of the
+       trace. This differs from the output when latency-format
+       is disabled, which includes an absolute timestamp.

 
   delay: This is just to help catch your eye a bit better. And
         needs to be fixed to be only relative to the same CPU.
 
   delay: This is just to help catch your eye a bit better. And
         needs to be fixed to be only relative to the same CPU.


@@ -440,7 +434,8 @@ Here are the available options:
   sym-addr:
    bash-4000  [01]  1477.606694: simple_strtoul <c0339346>
 
   sym-addr:
    bash-4000  [01]  1477.606694: simple_strtoul <c0339346>
 

-  verbose - This deals with the latency_trace file.
+  verbose - This deals with the trace file when the
+            latency-format option is enabled.

 
     bash  4000 1 0 00000000 00010a95 [58127d26] 1720.415ms \
     (+0.000ms): simple_strtoul (strict_strtoul)
 
     bash  4000 1 0 00000000 00010a95 [58127d26] 1720.415ms \
     (+0.000ms): simple_strtoul (strict_strtoul)


@@ -472,7 +467,7 @@ Here are the available options:
                the app is no longer running
 
                The lookup is performed when you read
                the app is no longer running
 
                The lookup is performed when you read

-               trace,trace_pipe,latency_trace. Example:
+               trace,trace_pipe. Example:

 
                a.out-1623  [000] 40874.465068: /root/a.out[+0x480] <-/root/a.out[+0
 x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
 
                a.out-1623  [000] 40874.465068: /root/a.out[+0x480] <-/root/a.out[+0
 x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]


@@ -481,6 +476,11 @@ x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
               every scheduling event. Will add overhead if
               there's a lot of tasks running at once.
 
               every scheduling event. Will add overhead if
               there's a lot of tasks running at once.
 

+  latency-format - This option changes the trace. When
+                   it is enabled, the trace displays
+                   additional information about the
+                   latencies, as described in "Latency
+                   trace format".

 
 sched_switch
 ------------
 
 sched_switch
 ------------


@@ -596,12 +596,13 @@ To reset the maximum, echo 0 into tracing_max_latency. Here is
 an example:
 
  # echo irqsoff > current_tracer
 an example:
 
  # echo irqsoff > current_tracer

+ # echo latency-format > trace_options

  # echo 0 > tracing_max_latency
  # echo 1 > tracing_enabled
  # ls -ltr
  [...]
  # echo 0 > tracing_enabled
  # echo 0 > tracing_max_latency
  # echo 1 > tracing_enabled
  # ls -ltr
  [...]
  # echo 0 > tracing_enabled

- # cat latency_trace
+ # cat trace

 # tracer: irqsoff
 #
 irqsoff latency trace v1.1.5 on 2.6.26
 # tracer: irqsoff
 #
 irqsoff latency trace v1.1.5 on 2.6.26


@@ -703,12 +704,13 @@ which preemption was disabled. The control of preemptoff tracer
 is much like the irqsoff tracer.
 
  # echo preemptoff > current_tracer
 is much like the irqsoff tracer.
 
  # echo preemptoff > current_tracer

+ # echo latency-format > trace_options

  # echo 0 > tracing_max_latency
  # echo 1 > tracing_enabled
  # ls -ltr
  [...]
  # echo 0 > tracing_enabled
  # echo 0 > tracing_max_latency
  # echo 1 > tracing_enabled
  # ls -ltr
  [...]
  # echo 0 > tracing_enabled

- # cat latency_trace
+ # cat trace

 # tracer: preemptoff
 #
 preemptoff latency trace v1.1.5 on 2.6.26-rc8
 # tracer: preemptoff
 #
 preemptoff latency trace v1.1.5 on 2.6.26-rc8


@@ -850,12 +852,13 @@ Again, using this trace is much like the irqsoff and preemptoff
 tracers.
 
  # echo preemptirqsoff > current_tracer
 tracers.
 
  # echo preemptirqsoff > current_tracer

+ # echo latency-format > trace_options

  # echo 0 > tracing_max_latency
  # echo 1 > tracing_enabled
  # ls -ltr
  [...]
  # echo 0 > tracing_enabled
  # echo 0 > tracing_max_latency
  # echo 1 > tracing_enabled
  # ls -ltr
  [...]
  # echo 0 > tracing_enabled

- # cat latency_trace
+ # cat trace

 # tracer: preemptirqsoff
 #
 preemptirqsoff latency trace v1.1.5 on 2.6.26-rc8
 # tracer: preemptirqsoff
 #
 preemptirqsoff latency trace v1.1.5 on 2.6.26-rc8


@@ -1012,11 +1015,12 @@ Instead of performing an 'ls', we will run 'sleep 1' under
 'chrt' which changes the priority of the task.
 
  # echo wakeup > current_tracer
 'chrt' which changes the priority of the task.
 
  # echo wakeup > current_tracer

+ # echo latency-format > trace_options

  # echo 0 > tracing_max_latency
  # echo 1 > tracing_enabled
  # chrt -f 5 sleep 1
  # echo 0 > tracing_enabled
  # echo 0 > tracing_max_latency
  # echo 1 > tracing_enabled
  # chrt -f 5 sleep 1
  # echo 0 > tracing_enabled

- # cat latency_trace
+ # cat trace

 # tracer: wakeup
 #
 wakeup latency trace v1.1.5 on 2.6.26-rc8
 # tracer: wakeup
 #
 wakeup latency trace v1.1.5 on 2.6.26-rc8