Hi James, I thought I'd mention this issue with multicore self-hosted trace. The perf command line syntax does not allow a sink "type" to be specified (e.g. @tmc_etf or @tmc_etr). For multicore, it doesn't make sense to specify a processor mapped sink as would be the case for single core trace. A sink "type" should be allowed to avoid the auto select default. In our case, the default is the ETF sink. Thanks, Steve C. On 12/10/2024 6:49 AM, James Clark wrote: > Previously the sink had to be specified, but now it auto selects one by > default. Including a sink in the examples causes issues when copy > pasting the command because it might not work if that sink isn't > present. Remove the sink from all the basic examples and create a new > section specifically about overriding the default one. > > Make the text a but more concise now that it's in the advanced section, > and similarly for removing the old kernel advice. > > Signed-off-by: James Clark <james.clark@xxxxxxxxxx> > --- > Documentation/trace/coresight/coresight.rst | 41 ++++++++----------- > .../userspace-api/perf_ring_buffer.rst | 4 +- > 2 files changed, 18 insertions(+), 27 deletions(-) > > diff --git a/Documentation/trace/coresight/coresight.rst b/Documentation/trace/coresight/coresight.rst > index d4f93d6a2d63..806699871b80 100644 > --- a/Documentation/trace/coresight/coresight.rst > +++ b/Documentation/trace/coresight/coresight.rst > @@ -462,44 +462,35 @@ queried by the perf command line tool: > > 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 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. > -On newer kernels the available sinks are listed in sysFS under > +provided along with configuration options within forward slashes '/' (see > +`Config option formats`_). > + > +Advanced Perf framework usage > +----------------------------- > + > +Sink selection > +~~~~~~~~~~~~~~ > + > +An appropriate sink will be selected automatically for use with Perf, but since > +there will typically be more than one sink, the name of the sink to use may be > +specified as a special config option prefixed with '@'. > + > +The available sinks are listed in sysFS under > ($SYSFS)/bus/event_source/devices/cs_etm/sinks/:: > > root@localhost:/sys/bus/event_source/devices/cs_etm/sinks# ls > tmc_etf0 tmc_etr0 tpiu0 > > -On older kernels, this may need to be found from the list of coresight devices, > -available under ($SYSFS)/bus/coresight/devices/:: > - > - root:~# ls /sys/bus/coresight/devices/ > - 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 > > -As mentioned above in section "Device Naming scheme", the names of the devices could > -look different from what is used in the example above. One must use the device names > -as it appears under the sysFS. > - > -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 > -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 [#third]_. > > -Advanced perf framework usage > ------------------------------ > - > AutoFDO analysis using the perf tools > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > @@ -508,7 +499,7 @@ 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/@tmc_etr0/u --per-thread > + perf record -e cs_etm//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. > @@ -572,7 +563,7 @@ 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/@tmc_etr0/u --per-thread taskset -c 2 ./sort > + $ perf record -e cs_etm//u --per-thread taskset -c 2 ./sort > Bubble sorting array of 30000 elements > 12543 ms > [ perf record: Woken up 35 times to write data ] > diff --git a/Documentation/userspace-api/perf_ring_buffer.rst b/Documentation/userspace-api/perf_ring_buffer.rst > index bde9d8cbc106..dc71544532ce 100644 > --- a/Documentation/userspace-api/perf_ring_buffer.rst > +++ b/Documentation/userspace-api/perf_ring_buffer.rst > @@ -627,7 +627,7 @@ regular ring buffer. > AUX events and AUX trace data are two different things. Let's see an > example:: > > - perf record -a -e cycles -e cs_etm/@tmc_etr0/ -- sleep 2 > + perf record -a -e cycles -e cs_etm// -- sleep 2 > > The above command enables two events: one is the event *cycles* from PMU > and another is the AUX event *cs_etm* from Arm CoreSight, both are saved > @@ -766,7 +766,7 @@ only record AUX trace data at a specific time point which users are > interested in. E.g. below gives an example of how to take snapshots > with 1 second interval with Arm CoreSight:: > > - perf record -e cs_etm/@tmc_etr0/u -S -a program & > + perf record -e cs_etm//u -S -a program & > PERFPID=$! > while true; do > kill -USR2 $PERFPID
