Update the documentation to reflect the new naming scheme with latest changes.
Reported-by: Leo Yan leo.yan@linaro.org Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Jonathan Corbet corbet@lwn.net Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- Documentation/trace/coresight.txt | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-)
diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt index efbc832..7b427cf 100644 --- a/Documentation/trace/coresight.txt +++ b/Documentation/trace/coresight.txt @@ -326,16 +326,20 @@ amount of processor cores), the "cs_etm" PMU will be listed only once. A Coresight PMU works the same way as any other PMU, 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 ($SYSFS)/bus/coresight/devices: +work with needs to be specified as an event option. +On newer kernels the available sinks are listed in sysFS under: +($SYSFS)/bus/event_source/devices/cs_etm/sinks/
- 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@localhost:/sys/bus/event_source/devices/cs_etm/sinks# ls + tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@20070000.etr/u --per-thread program +On older kernels, this may need to be found from the list of coresight devices, +available under ($SYSFS)/bus/coresight/devices/: + + root@localhost:/sys/bus/coresight/devices# ls + etm0 etm1 etm2 etm3 etm4 etm5 funnel0 funnel1 funnel2 replicator0 stm0 tmc_etf0 tmc_etr0 tpiu0 + + root@linaro-nano:~# perf record -e cs_etm/@tmc_etr0/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 sink @@ -352,7 +356,7 @@ perf can be used to record and analyze trace of programs. Execution can be recorded using 'perf record' with the cs_etm event, specifying the name of the sink to record to, e.g:
- perf record -e cs_etm/@20070000.etr/u --per-thread + perf record -e cs_etm/@tmc_etr0/u --per-thread
The 'perf report' and 'perf script' commands can be used to analyze execution, synthesizing instruction and branch events from the instruction trace. @@ -381,7 +385,7 @@ sort example is from the AutoFDO tutorial (https://gcc.gnu.org/wiki/AutoFDO/Tuto Bubble sorting array of 30000 elements 5910 ms
- $ perf record -e cs_etm/@20070000.etr/u --per-thread taskset -c 2 ./sort + $ perf record -e cs_etm/@tmc_etr0/u --per-thread taskset -c 2 ./sort Bubble sorting array of 30000 elements 12543 ms [ perf record: Woken up 35 times to write data ] @@ -405,7 +409,7 @@ 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 +root@genericarmv8:~# ls /sys/bus/coresight/devices/stm0 enable_source hwevent_select port_enable subsystem uevent hwevent_enable mgmt port_select traceid root@genericarmv8:~# @@ -413,14 +417,14 @@ 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 +root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/tmc_etf0/enable_sink +root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/stm0/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:~# ls -l /dev/stm0 +crw------- 1 root root 10, 61 Jan 3 18:11 /dev/stm0 root@genericarmv8:~#
Details on how to use the generic STM API can be found here [2].
Hi Suzuki,
On Thu, May 30, 2019 at 04:11:17PM +0100, Suzuki K Poulose wrote:
Update the documentation to reflect the new naming scheme with latest changes.
Reported-by: Leo Yan leo.yan@linaro.org Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Jonathan Corbet corbet@lwn.net Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com
Documentation/trace/coresight.txt | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-)
diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt index efbc832..7b427cf 100644 --- a/Documentation/trace/coresight.txt +++ b/Documentation/trace/coresight.txt @@ -326,16 +326,20 @@ amount of processor cores), the "cs_etm" PMU will be listed only once. A Coresight PMU works the same way as any other PMU, 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 ($SYSFS)/bus/coresight/devices: +work with needs to be specified as an event option. +On newer kernels the available sinks are listed in sysFS under: +($SYSFS)/bus/event_source/devices/cs_etm/sinks/
- root@linaro-nano:~# ls /sys/bus/coresight/devices/
20010000.etf 20040000.funnel 20100000.stm 22040000.etm22140000.etm 230c0000.funnel 23240000.etm 20030000.tpiu20070000.etr 20120000.replicator 220c0000.funnel23040000.etm 23140000.etm 23340000.etm
- root@localhost:/sys/bus/event_source/devices/cs_etm/sinks# ls
- tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@20070000.etr/u --per-thread program
+On older kernels, this may need to be found from the list of coresight devices, +available under ($SYSFS)/bus/coresight/devices/:
- root@localhost:/sys/bus/coresight/devices# ls
- etm0 etm1 etm2 etm3 etm4 etm5 funnel0 funnel1 funnel2 replicator0 stm0 tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@tmc_etr0/u --per-thread program
On the "older" kernels you are referring to one would find the original naming convention. Everything else looks good to me.
Mathieu
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 sink @@ -352,7 +356,7 @@ perf can be used to record and analyze trace of programs. Execution can be recorded using 'perf record' with the cs_etm event, specifying the name of the sink to record to, e.g:
- perf record -e cs_etm/@20070000.etr/u --per-thread
- perf record -e cs_etm/@tmc_etr0/u --per-thread
The 'perf report' and 'perf script' commands can be used to analyze execution, synthesizing instruction and branch events from the instruction trace. @@ -381,7 +385,7 @@ sort example is from the AutoFDO tutorial (https://gcc.gnu.org/wiki/AutoFDO/Tuto Bubble sorting array of 30000 elements 5910 ms
- $ perf record -e cs_etm/@20070000.etr/u --per-thread taskset -c 2 ./sort
- $ perf record -e cs_etm/@tmc_etr0/u --per-thread taskset -c 2 ./sort Bubble sorting array of 30000 elements 12543 ms [ perf record: Woken up 35 times to write data ]
@@ -405,7 +409,7 @@ 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 +root@genericarmv8:~# ls /sys/bus/coresight/devices/stm0 enable_source hwevent_select port_enable subsystem uevent hwevent_enable mgmt port_select traceid root@genericarmv8:~# @@ -413,14 +417,14 @@ 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 +root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/tmc_etf0/enable_sink +root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/stm0/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:~# ls -l /dev/stm0 +crw------- 1 root root 10, 61 Jan 3 18:11 /dev/stm0 root@genericarmv8:~# Details on how to use the generic STM API can be found here [2]. -- 2.7.4
Hi Mathieu,
On 03/06/2019 20:01, Mathieu Poirier wrote:
Hi Suzuki,
On Thu, May 30, 2019 at 04:11:17PM +0100, Suzuki K Poulose wrote:
Update the documentation to reflect the new naming scheme with latest changes.
Reported-by: Leo Yan leo.yan@linaro.org Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Jonathan Corbet corbet@lwn.net Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com
Documentation/trace/coresight.txt | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-)
diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt index efbc832..7b427cf 100644 --- a/Documentation/trace/coresight.txt +++ b/Documentation/trace/coresight.txt @@ -326,16 +326,20 @@ amount of processor cores), the "cs_etm" PMU will be listed only once. A Coresight PMU works the same way as any other PMU, 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 ($SYSFS)/bus/coresight/devices: +work with needs to be specified as an event option. +On newer kernels the available sinks are listed in sysFS under: +($SYSFS)/bus/event_source/devices/cs_etm/sinks/
- root@linaro-nano:~# ls /sys/bus/coresight/devices/
20010000.etf 20040000.funnel 20100000.stm 22040000.etm22140000.etm 230c0000.funnel 23240000.etm 20030000.tpiu20070000.etr 20120000.replicator 220c0000.funnel23040000.etm 23140000.etm 23340000.etm
- root@localhost:/sys/bus/event_source/devices/cs_etm/sinks# ls
- tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@20070000.etr/u --per-thread program
+On older kernels, this may need to be found from the list of coresight devices, +available under ($SYSFS)/bus/coresight/devices/:
- root@localhost:/sys/bus/coresight/devices# ls
- etm0 etm1 etm2 etm3 etm4 etm5 funnel0 funnel1 funnel2 replicator0 stm0 tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@tmc_etr0/u --per-thread program
On the "older" kernels you are referring to one would find the original naming convention. Everything else looks good to me.
True, but do we care what we see there ? All we care about is the location, where to find them. I could fix it, if you think thats needed.
Cheers Suzuki
Hi Suzuki,
On Thu, Jun 06, 2019 at 05:21:19PM +0100, Suzuki K Poulose wrote:
Hi Mathieu,
On 03/06/2019 20:01, Mathieu Poirier wrote:
Hi Suzuki,
On Thu, May 30, 2019 at 04:11:17PM +0100, Suzuki K Poulose wrote:
Update the documentation to reflect the new naming scheme with latest changes.
Reported-by: Leo Yan leo.yan@linaro.org Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Jonathan Corbet corbet@lwn.net Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com
Documentation/trace/coresight.txt | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-)
diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt index efbc832..7b427cf 100644 --- a/Documentation/trace/coresight.txt +++ b/Documentation/trace/coresight.txt @@ -326,16 +326,20 @@ amount of processor cores), the "cs_etm" PMU will be listed only once. A Coresight PMU works the same way as any other PMU, i.e the name of the PMU is listed along with configuration options within forward slashes '/'. Since a Coresight system will typically have more than one sink, the name of the sink to -work with needs to be specified as an event option. Names for sink to choose -from are listed in sysFS under ($SYSFS)/bus/coresight/devices: +work with needs to be specified as an event option. +On newer kernels the available sinks are listed in sysFS under: +($SYSFS)/bus/event_source/devices/cs_etm/sinks/
- root@linaro-nano:~# ls /sys/bus/coresight/devices/
20010000.etf 20040000.funnel 20100000.stm 22040000.etm22140000.etm 230c0000.funnel 23240000.etm 20030000.tpiu20070000.etr 20120000.replicator 220c0000.funnel23040000.etm 23140000.etm 23340000.etm
- root@localhost:/sys/bus/event_source/devices/cs_etm/sinks# ls
- tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@20070000.etr/u --per-thread program
+On older kernels, this may need to be found from the list of coresight devices, +available under ($SYSFS)/bus/coresight/devices/:
- root@localhost:/sys/bus/coresight/devices# ls
- etm0 etm1 etm2 etm3 etm4 etm5 funnel0 funnel1 funnel2 replicator0 stm0 tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@tmc_etr0/u --per-thread program
On the "older" kernels you are referring to one would find the original naming convention. Everything else looks good to me.
True, but do we care what we see there ? All we care about is the location, where to find them. I could fix it, if you think thats needed.
IIUC, either the old kernel or newer kernel, both we can find the event from ($SYSFS)/bus/event_source/devices/cs_etm/sinks/; the only difference between them is the naming convention.
So the doc can use the same location to find event for both new and old kernel, and explain the naming convention difference?
Thanks, Leo Yan
Hi Leo,
A Coresight PMU works the same way as any other PMU, i.e the name of the PMU is listed along with configuration options within forward slashes '/'. Since a Coresight system will typically have more than one sink, the name of the sink to -work with needs to be specified as an event option. Names for sink to choose -from are listed in sysFS under ($SYSFS)/bus/coresight/devices: +work with needs to be specified as an event option. +On newer kernels the available sinks are listed in sysFS under: +($SYSFS)/bus/event_source/devices/cs_etm/sinks/
- root@linaro-nano:~# ls /sys/bus/coresight/devices/
20010000.etf 20040000.funnel 20100000.stm 22040000.etm22140000.etm 230c0000.funnel 23240000.etm 20030000.tpiu20070000.etr 20120000.replicator 220c0000.funnel23040000.etm 23140000.etm 23340000.etm
- root@localhost:/sys/bus/event_source/devices/cs_etm/sinks# ls
- tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@20070000.etr/u --per-thread program
+On older kernels, this may need to be found from the list of coresight devices, +available under ($SYSFS)/bus/coresight/devices/:
- root@localhost:/sys/bus/coresight/devices# ls
- etm0 etm1 etm2 etm3 etm4 etm5 funnel0 funnel1 funnel2 replicator0 stm0 tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@tmc_etr0/u --per-thread program
On the "older" kernels you are referring to one would find the original naming convention. Everything else looks good to me.
True, but do we care what we see there ? All we care about is the location, where to find them. I could fix it, if you think thats needed.
IIUC, either the old kernel or newer kernel, both we can find the event from ($SYSFS)/bus/event_source/devices/cs_etm/sinks/; the only difference between them is the naming convention.
The cs_etm/sinks was only added with the CPU-wide trace support. So, if someone refers to this document alone and then tries to do something on on older kernel, which is quite possible for a production device running a stable kernel, {s,}he might be surprised.
So the doc can use the same location to find event for both new and old kernel, and explain the naming convention difference?
My question is really, does the naming convention matter ? What you see under the directory is the name. But yes, I am open to add a section to explain the fact that we changed the naming scheme, if everyone agrees to it.
Cheers Suzuki
Hi Suzuki,
On Fri, Jun 07, 2019 at 09:40:48AM +0100, Suzuki K Poulose wrote:
Hi Leo,
A Coresight PMU works the same way as any other PMU, i.e the name of the PMU is listed along with configuration options within forward slashes '/'. Since a Coresight system will typically have more than one sink, the name of the sink to -work with needs to be specified as an event option. Names for sink to choose -from are listed in sysFS under ($SYSFS)/bus/coresight/devices: +work with needs to be specified as an event option. +On newer kernels the available sinks are listed in sysFS under: +($SYSFS)/bus/event_source/devices/cs_etm/sinks/
- root@linaro-nano:~# ls /sys/bus/coresight/devices/
20010000.etf 20040000.funnel 20100000.stm 22040000.etm22140000.etm 230c0000.funnel 23240000.etm 20030000.tpiu20070000.etr 20120000.replicator 220c0000.funnel23040000.etm 23140000.etm 23340000.etm
- root@localhost:/sys/bus/event_source/devices/cs_etm/sinks# ls
- tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@20070000.etr/u --per-thread program
+On older kernels, this may need to be found from the list of coresight devices, +available under ($SYSFS)/bus/coresight/devices/:
- root@localhost:/sys/bus/coresight/devices# ls
- etm0 etm1 etm2 etm3 etm4 etm5 funnel0 funnel1 funnel2 replicator0 stm0 tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@tmc_etr0/u --per-thread program
On the "older" kernels you are referring to one would find the original naming convention. Everything else looks good to me.
True, but do we care what we see there ? All we care about is the location, where to find them. I could fix it, if you think thats needed.
IIUC, either the old kernel or newer kernel, both we can find the event from ($SYSFS)/bus/event_source/devices/cs_etm/sinks/; the only difference between them is the naming convention.
The cs_etm/sinks was only added with the CPU-wide trace support. So, if someone refers to this document alone and then tries to do something on on older kernel, which is quite possible for a production device running a stable kernel, {s,}he might be surprised.
Okay, understand now. Thanks for clarification.
So the doc can use the same location to find event for both new and old kernel, and explain the naming convention difference?
My question is really, does the naming convention matter ? What you see under the directory is the name. But yes, I am open to add a section to explain the fact that we changed the naming scheme, if everyone agrees to it.
The naming convention is not important for the developers who are familiar with CoreSight development; later who is the first time to access kernel CoreSight modules and don't know the history for naming scheme, the related documentation will be friendly and reduce the barrier for using it.
I have no strong opinion for this, seems to me another choice is to describe the older kernel with old naming scheme, something like below:
On older kernels, this may need to be found from the list of coresight devices, available under ($SYSFS)/bus/coresight/devices/ with old naming scheme:
root@linaro-nano:~# ls /sys/bus/coresight/devices/ 20010000.etf 20040000.funnel 20100000.stm 22040000.etm> Cheers 22140000.etm 230c0000.funnel 23240000.etm 20030000.tpiu > Suzuki 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
Thanks, Leo Yan
On Fri, 7 Jun 2019 at 02:40, Suzuki K Poulose suzuki.poulose@arm.com wrote:
Hi Leo,
A Coresight PMU works the same way as any other PMU, 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 ($SYSFS)/bus/coresight/devices: +work with needs to be specified as an event option. +On newer kernels the available sinks are listed in sysFS under: +($SYSFS)/bus/event_source/devices/cs_etm/sinks/
- root@linaro-nano:~# ls /sys/bus/coresight/devices/
20010000.etf 20040000.funnel 20100000.stm 22040000.etm22140000.etm 230c0000.funnel 23240000.etm 20030000.tpiu20070000.etr 20120000.replicator 220c0000.funnel23040000.etm 23140000.etm 23340000.etm
- root@localhost:/sys/bus/event_source/devices/cs_etm/sinks# ls
- tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@20070000.etr/u --per-thread program
+On older kernels, this may need to be found from the list of coresight devices, +available under ($SYSFS)/bus/coresight/devices/:
- root@localhost:/sys/bus/coresight/devices# ls
- etm0 etm1 etm2 etm3 etm4 etm5 funnel0 funnel1 funnel2 replicator0 stm0 tmc_etf0 tmc_etr0 tpiu0
- root@linaro-nano:~# perf record -e cs_etm/@tmc_etr0/u --per-thread program
On the "older" kernels you are referring to one would find the original naming convention. Everything else looks good to me.
True, but do we care what we see there ? All we care about is the location, where to find them. I could fix it, if you think thats needed.
IIUC, either the old kernel or newer kernel, both we can find the event from ($SYSFS)/bus/event_source/devices/cs_etm/sinks/; the only difference between them is the naming convention.
The cs_etm/sinks was only added with the CPU-wide trace support. So, if someone refers to this document alone and then tries to do something on on older kernel, which is quite possible for a production device running a stable kernel, {s,}he might be surprised.
So the doc can use the same location to find event for both new and old kernel, and explain the naming convention difference?
My question is really, does the naming convention matter ? What you see under the directory is the name. But yes, I am open to add a section to explain the fact that we changed the naming scheme, if everyone agrees to it.
I think it would be preferable to mention the change - just a small section that describes what happened and the reason for doing so will be fine.
Cheers Suzuki
-
Leo Yan -
Mathieu Poirier -
Suzuki K Poulose