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coresight: Grouping all perf tools oriented section together 

This patch groups together section pertaining to the perf tools.  That way
everything is at the same place rather than spread out.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Mathieu Poirier 2018-04-17 10:08:07 -06:00 committed by Jonathan Corbet
parent f29816b496
commit 87bf4d68a4
1 changed files with 36 additions and 36 deletions
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72
Documentation/trace/coresight.txt
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@ -345,42 +345,7 @@ More information on the above and other example on how to use Coresight with
the perf tools can be found in the "HOWTO.md" file of the openCSD gitHub
repository [3].
How to use the STM module
-------------------------
Using the System Trace Macrocell module is the same as the tracers - the only
difference is that clients are driving the trace capture rather
than the program flow through the code.
As with any other CoreSight component, specifics about the STM tracer can be
found in sysfs with more information on each entry being found in [1]:
root@genericarmv8:~# ls /sys/bus/coresight/devices/20100000.stm
enable_source hwevent_select port_enable subsystem uevent
hwevent_enable mgmt port_select traceid
root@genericarmv8:~#
Like any other source a sink needs to be identified and the STM enabled before
being used:
root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/20010000.etf/enable_sink
root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/20100000.stm/enable_source
From there user space applications can request and use channels using the devfs
interface provided for that purpose by the generic STM API:
root@genericarmv8:~# ls -l /dev/20100000.stm
crw------- 1 root root 10, 61 Jan 3 18:11 /dev/20100000.stm
root@genericarmv8:~#
Details on how to use the generic STM API can be found here [2].
[1]. Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
[2]. Documentation/trace/stm.txt
Using perf tools
----------------
2.1) AutoFDO analysis using the perf tools:
perf can be used to record and analyze trace of programs.
@ -428,3 +393,38 @@ sort example is from the AutoFDO tutorial (https://gcc.gnu.org/wiki/AutoFDO/Tuto
$ taskset -c 2 ./sort_autofdo
Bubble sorting array of 30000 elements
5806 ms
How to use the STM module
-------------------------
Using the System Trace Macrocell module is the same as the tracers - the only
difference is that clients are driving the trace capture rather
than the program flow through the code.
As with any other CoreSight component, specifics about the STM tracer can be
found in sysfs with more information on each entry being found in [1]:
root@genericarmv8:~# ls /sys/bus/coresight/devices/20100000.stm
enable_source hwevent_select port_enable subsystem uevent
hwevent_enable mgmt port_select traceid
root@genericarmv8:~#
Like any other source a sink needs to be identified and the STM enabled before
being used:
root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/20010000.etf/enable_sink
root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/20100000.stm/enable_source
From there user space applications can request and use channels using the devfs
interface provided for that purpose by the generic STM API:
root@genericarmv8:~# ls -l /dev/20100000.stm
crw------- 1 root root 10, 61 Jan 3 18:11 /dev/20100000.stm
root@genericarmv8:~#
Details on how to use the generic STM API can be found here [2].
[1]. Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
[2]. Documentation/trace/stm.txt
[3]. https://github.com/Linaro/perf-opencsd