Commit d28daf92 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

Merge branch 'tracing/core' of...

Merge branch 'tracing/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing into tracing/core
parents ed011b22 4a88d44a
......@@ -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).
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.
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:
......@@ -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
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:
......@@ -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
trace via the latency_trace file.
trace with the latency-format option enabled.
"preemptoff"
......@@ -307,8 +300,8 @@ the lowest priority thread (pid 0).
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
......@@ -380,9 +373,10 @@ explains which is which.
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.
......@@ -440,7 +434,8 @@ Here are the available options:
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)
......@@ -472,7 +467,7 @@ Here are the available options:
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]
......@@ -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.
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
------------
......@@ -596,12 +596,13 @@ To reset the maximum, echo 0 into tracing_max_latency. Here is
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
# cat latency_trace
# cat trace
# 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
# echo latency-format > trace_options
# 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
......@@ -850,12 +852,13 @@ Again, using this trace is much like the irqsoff and preemptoff
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
# cat latency_trace
# cat trace
# 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
# echo latency-format > trace_options
# 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
......
......@@ -409,6 +409,9 @@ static int init_preds(struct ftrace_event_call *call)
struct filter_pred *pred;
int i;
if (call->filter)
return 0;
filter = call->filter = kzalloc(sizeof(*filter), GFP_KERNEL);
if (!call->filter)
return -ENOMEM;
......@@ -447,11 +450,9 @@ static int init_subsystem_preds(struct event_subsystem *system)
if (strcmp(call->system, system->name) != 0)
continue;
if (!call->filter) {
err = init_preds(call);
if (err)
return err;
}
err = init_preds(call);
if (err)
return err;
}
return 0;
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment