[PATCH 0/3] coresight: Refresh documenation

[PATCH 0/3] coresight: Refresh documenation

[Mathieu Poirier]

Now that the perf tools CoreSight support is upstream this set adds
documentation to go with it and move things around so that topics 
are located together. 

Mathieu Poirier (3):
  coresight: Remove obsolete reference to "owner" in CoreSight
    descriptor
  coresight: Add section for integration with the perf tools
  coresight: Grouping all perf tools oriented section together

 Documentation/trace/coresight.txt | 101 ++++++++++++++++++++++++++++----------
 1 file changed, 74 insertions(+), 27 deletions(-)

-- 
2.7.4

[PATCH 1/3] coresight: Remove obsolete reference to "owner" in CoreSight descriptor

[Mathieu Poirier]

Field "owner" of struct coresight_desc has been removed a while back but
the documentation was not updated to reflect the changes.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 Documentation/trace/coresight.txt | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt
index 6f0120c3a4f1..710c75b6c73f 100644
--- a/Documentation/trace/coresight.txt
+++ b/Documentation/trace/coresight.txt
@@ -187,9 +187,6 @@ that can be performed on them (see "struct coresight_ops").  The
 specific to that component only.  "Implementation defined" customisations are
 expected to be accessed and controlled using those entries.
 
-Last but not least, "struct module *owner" is expected to be set to reflect
-the information carried in "THIS_MODULE".
-
 How to use the tracer modules
 -----------------------------
 
-- 
2.7.4

[PATCH 2/3] coresight: Add section for integration with the perf tools

[Mathieu Poirier]

Adding a section that document how to use the Coresight framework and
drivers from the perf tools.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 Documentation/trace/coresight.txt | 50 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt
index 710c75b6c73f..8caae8050a60 100644
--- a/Documentation/trace/coresight.txt
+++ b/Documentation/trace/coresight.txt
@@ -187,9 +187,18 @@ that can be performed on them (see "struct coresight_ops").  The
 specific to that component only.  "Implementation defined" customisations are
 expected to be accessed and controlled using those entries.
 
+
 How to use the tracer modules
 -----------------------------
 
+There is two ways to use the Coresight framework: 1) using the perf cmd line
+tools and 2) interacting directly with the Coresight devices using the sysFS
+interface.  Preference is given to the former as using the sysFS interface
+requires a deep understanding of the Coresight HW.  The following sections
+provide details on using both methods.
+
+1) Using the sysFS interface:
+
 Before trace collection can start, a coresight sink needs to be identify.
 There is no limit on the amount of sinks (nor sources) that can be enabled at
 any given moment.  As a generic operation, all device pertaining to the sink
@@ -295,6 +304,47 @@ Instruction     13570831        0x8026B584      E28DD00C        false   ADD
 Instruction     0       0x8026B588      E8BD8000        true    LDM      sp!,{pc}
 Timestamp                                       Timestamp: 17107041535
 
+2) Using perf framework:
+
+Coresight tracers are represented using the Perf framework's Performance
+Monitoring Unit (PMU) abstraction.  As such the perf framework takes charge of
+controlling when tracing gets enabled based on when the process of interest is
+scheduled.  When configured in a system, Coresight PMUs will be listed when
+queried by the perf command line tool:
+
+	linaro@linaro-nano:~$ ./perf list pmu
+
+		List of pre-defined events (to be used in -e):
+
+		cs_etm//                                    [Kernel PMU event]
+
+	linaro@linaro-nano:~$
+
+Regardless of the number of tracers available in a system (usually equal to the
+amount of processor core), the "cs_etm" PMU will be listed only once.
+
+A Coresight PMU works the same way as any other PMUs, i.e the name of the PMU is
+listed along with configuration options within forward slashes '/'.  Since a
+Coresight system will typically have more than one sink, the name of the sink to
+work with needs to be specified as an event option.  Names for sink to choose
+from are listed in sysFS under ($SYSFS)/bus/coresight/devices:
+
+	root@linaro-nano:~# ls /sys/bus/coresight/devices/
+		20010000.etf   20040000.funnel  20100000.stm  22040000.etm
+		22140000.etm  230c0000.funnel  23240000.etm 20030000.tpiu
+		20070000.etr     20120000.replicator  220c0000.funnel
+		23040000.etm  23140000.etm     23340000.etm
+
+	root@linaro-nano:~# perf record -e cs_etm/@20070000.etr/u --per-thread program
+
+The syntax within the forward slashes '/' is important.  The '@' character
+tells the parser that a sink is about to be specified and that this is the IP
+to use for the trace session.
+
+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
 -------------------------
 
-- 
2.7.4

Re: [PATCH 2/3] coresight: Add section for integration with the perf tools

[Randy Dunlap]

On 04/16/2018 12:35 PM, Mathieu Poirier wrote:
> Adding a section that document how to use the Coresight framework and
> drivers from the perf tools.
> 
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
>  Documentation/trace/coresight.txt | 50 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
> 
> diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt
> index 710c75b6c73f..8caae8050a60 100644
> --- a/Documentation/trace/coresight.txt
> +++ b/Documentation/trace/coresight.txt
> @@ -187,9 +187,18 @@ that can be performed on them (see "struct coresight_ops").  The
>  specific to that component only.  "Implementation defined" customisations are
>  expected to be accessed and controlled using those entries.
>  
> +
>  How to use the tracer modules
>  -----------------------------
>  
> +There is two ways to use the Coresight framework: 1) using the perf cmd line

   There are two ways

> +tools and 2) interacting directly with the Coresight devices using the sysFS
> +interface.  Preference is given to the former as using the sysFS interface
> +requires a deep understanding of the Coresight HW.  The following sections
> +provide details on using both methods.
> +
> +1) Using the sysFS interface:
> +
>  Before trace collection can start, a coresight sink needs to be identify.

                                                                   identified.

>  There is no limit on the amount of sinks (nor sources) that can be enabled at
>  any given moment.  As a generic operation, all device pertaining to the sink
> @@ -295,6 +304,47 @@ Instruction     13570831        0x8026B584      E28DD00C        false   ADD
>  Instruction     0       0x8026B588      E8BD8000        true    LDM      sp!,{pc}
>  Timestamp                                       Timestamp: 17107041535
>  
> +2) Using perf framework:
> +
> +Coresight tracers are represented using the Perf framework's Performance
> +Monitoring Unit (PMU) abstraction.  As such the perf framework takes charge of
> +controlling when tracing gets enabled based on when the process of interest is
> +scheduled.  When configured in a system, Coresight PMUs will be listed when
> +queried by the perf command line tool:
> +
> +	linaro@linaro-nano:~$ ./perf list pmu
> +
> +		List of pre-defined events (to be used in -e):
> +
> +		cs_etm//                                    [Kernel PMU event]
> +
> +	linaro@linaro-nano:~$
> +
> +Regardless of the number of tracers available in a system (usually equal to the
> +amount of processor core), the "cs_etm" PMU will be listed only once.

?                      cores),

> +
> +A Coresight PMU works the same way as any other PMUs, i.e the name of the PMU is

                                         any other PMU, i.e.

> +listed along with configuration options within forward slashes '/'.  Since a
> +Coresight system will typically have more than one sink, the name of the sink to
> +work with needs to be specified as an event option.  Names for sink to choose
> +from are listed in sysFS under ($SYSFS)/bus/coresight/devices:
> +
> +	root@linaro-nano:~# ls /sys/bus/coresight/devices/
> +		20010000.etf   20040000.funnel  20100000.stm  22040000.etm
> +		22140000.etm  230c0000.funnel  23240000.etm 20030000.tpiu
> +		20070000.etr     20120000.replicator  220c0000.funnel
> +		23040000.etm  23140000.etm     23340000.etm
> +
> +	root@linaro-nano:~# perf record -e cs_etm/@20070000.etr/u --per-thread program
> +
> +The syntax within the forward slashes '/' is important.  The '@' character
> +tells the parser that a sink is about to be specified and that this is the IP

Can we get away from using "IP" and call it a device or (hardware) module or
something more descriptive?

> +to use for the trace session.
> +
> +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].


-- 
~Randy

Re: [PATCH 2/3] coresight: Add section for integration with the perf tools

[Mathieu Poirier]

On 16 April 2018 at 13:48, Randy Dunlap <rdunlap@infradead.org> wrote:
> On 04/16/2018 12:35 PM, Mathieu Poirier wrote:
>> Adding a section that document how to use the Coresight framework and
>> drivers from the perf tools.
>>
>> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
>> ---
>>  Documentation/trace/coresight.txt | 50 +++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 50 insertions(+)
>>
>> diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt
>> index 710c75b6c73f..8caae8050a60 100644
>> --- a/Documentation/trace/coresight.txt
>> +++ b/Documentation/trace/coresight.txt
>> @@ -187,9 +187,18 @@ that can be performed on them (see "struct coresight_ops").  The
>>  specific to that component only.  "Implementation defined" customisations are
>>  expected to be accessed and controlled using those entries.
>>
>> +
>>  How to use the tracer modules
>>  -----------------------------
>>
>> +There is two ways to use the Coresight framework: 1) using the perf cmd line
>
>    There are two ways
>
>> +tools and 2) interacting directly with the Coresight devices using the sysFS
>> +interface.  Preference is given to the former as using the sysFS interface
>> +requires a deep understanding of the Coresight HW.  The following sections
>> +provide details on using both methods.
>> +
>> +1) Using the sysFS interface:
>> +
>>  Before trace collection can start, a coresight sink needs to be identify.
>
>                                                                    identified.
>
>>  There is no limit on the amount of sinks (nor sources) that can be enabled at
>>  any given moment.  As a generic operation, all device pertaining to the sink
>> @@ -295,6 +304,47 @@ Instruction     13570831        0x8026B584      E28DD00C        false   ADD
>>  Instruction     0       0x8026B588      E8BD8000        true    LDM      sp!,{pc}
>>  Timestamp                                       Timestamp: 17107041535
>>
>> +2) Using perf framework:
>> +
>> +Coresight tracers are represented using the Perf framework's Performance
>> +Monitoring Unit (PMU) abstraction.  As such the perf framework takes charge of
>> +controlling when tracing gets enabled based on when the process of interest is
>> +scheduled.  When configured in a system, Coresight PMUs will be listed when
>> +queried by the perf command line tool:
>> +
>> +     linaro@linaro-nano:~$ ./perf list pmu
>> +
>> +             List of pre-defined events (to be used in -e):
>> +
>> +             cs_etm//                                    [Kernel PMU event]
>> +
>> +     linaro@linaro-nano:~$
>> +
>> +Regardless of the number of tracers available in a system (usually equal to the
>> +amount of processor core), the "cs_etm" PMU will be listed only once.
>
> ?                      cores),
>
>> +
>> +A Coresight PMU works the same way as any other PMUs, i.e the name of the PMU is
>
>                                          any other PMU, i.e.
>
>> +listed along with configuration options within forward slashes '/'.  Since a
>> +Coresight system will typically have more than one sink, the name of the sink to
>> +work with needs to be specified as an event option.  Names for sink to choose
>> +from are listed in sysFS under ($SYSFS)/bus/coresight/devices:
>> +
>> +     root@linaro-nano:~# ls /sys/bus/coresight/devices/
>> +             20010000.etf   20040000.funnel  20100000.stm  22040000.etm
>> +             22140000.etm  230c0000.funnel  23240000.etm 20030000.tpiu
>> +             20070000.etr     20120000.replicator  220c0000.funnel
>> +             23040000.etm  23140000.etm     23340000.etm
>> +
>> +     root@linaro-nano:~# perf record -e cs_etm/@20070000.etr/u --per-thread program
>> +
>> +The syntax within the forward slashes '/' is important.  The '@' character
>> +tells the parser that a sink is about to be specified and that this is the IP
>
> Can we get away from using "IP" and call it a device or (hardware) module or
> something more descriptive?

Sure thing.

Thanks for taking the time to read the patch and providing comments.

Mathieu

>
>> +to use for the trace session.
>> +
>> +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].
>
>
> --
> ~Randy

[PATCH 3/3] coresight: Grouping all perf tools oriented section together

[Mathieu Poirier]

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>
---
 Documentation/trace/coresight.txt | 72 +++++++++++++++++++--------------------
 1 file changed, 36 insertions(+), 36 deletions(-)

diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt
index 8caae8050a60..32c5b159e8fc 100644
--- a/Documentation/trace/coresight.txt
+++ b/Documentation/trace/coresight.txt
@@ -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
-- 
2.7.4