In the coresight world there can be more than one sink to aggregate trace data generated by CPUs, hence the need for users to select which one to use from the perf command line. Up until now sysfs was used to communicate sink information to the kernel but that was never the right way to proceed because it breaks when more than one perf session are created at the same time. The situation was manageable when working with per-thread scenarios where a single HW trace event is created but in CPU-wide mode a HW trace event is created for each CPU that is specified on the perf command line, taking us back to the concurrency problem we have when dealing with multiple per-thread session. This work fits in a wider scheme to support CPU-wide trace scenarios on CoreSight that is available here [1]. The first step in that venture is to address sysfs concurrency issues, which this patchset does. The main difference with V4 is the usage of a CoreSight sink's HW start address (u64) to uniquely identify a sink, negating the need to use the component's name (char *). By using a u64 we can theoretically add the sink information to the perf_event_attr structure, avoiding the need to add a new perf ioctl(). On flip side it would introduce a very specific CoreSight field to a structure that is generic. I have opted for the ioctl() method, let me know if you want me to proceed with the latter. Regards, Mathieu # Before this set: root@juno:/home/linaro# perf record -e cs_etm/@20070000.etr/ -C 2,3 sleep 1 failed to mmap with 12 (Cannot allocate memory) # After this set: root@juno:/home/linaro# perf record -e cs_etm/@20070000.etr/ -C 2,3 sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 4.145 MB perf.data ] [1]. https://git.linaro.org/people/mathieu.poirier/coresight.git/log/?h=cpu-wide-coresight --- Changes for V5: . Went from a char * to a u64 for ioctl argument (GKH). . Added a better description of the problem being fixed to the cover letter (GKH). Changes for V4: . Made passing of information between ioctl() and PMU simpler. Mathieu Poirier (6): perf: Introduce ioctl to communicate driver configuration to kernel perf/core: Use ioctl to communicate driver configuration to kernel perf/aux: Make perf_event accessible to setup_aux() coresight: Use PMU driver configuration for sink selection perf tools: Make perf_evsel accessible to PMU driver configuration code perf tools: Use ioctl function to send sink information to kernel arch/s390/kernel/perf_cpum_sf.c | 6 +- arch/x86/events/intel/bts.c | 4 +- arch/x86/events/intel/pt.c | 5 +- drivers/hwtracing/coresight/coresight-etm-perf.c | 80 +++++++++++++++++----- drivers/perf/arm_spe_pmu.c | 6 +- include/linux/perf_event.h | 40 ++++++++++- include/uapi/linux/perf_event.h | 1 + kernel/events/core.c | 67 +++++++++++++++++++ kernel/events/ring_buffer.c | 2 +- tools/include/uapi/linux/perf_event.h | 1 + tools/perf/arch/arm/util/cs-etm.c | 84 +++++++++++++++++++++++- tools/perf/arch/arm/util/cs-etm.h | 3 +- tools/perf/util/drv_configs.c | 30 ++------- tools/perf/util/evsel.c | 6 ++ tools/perf/util/evsel.h | 1 + tools/perf/util/pmu.h | 3 +- 16 files changed, 287 insertions(+), 52 deletions(-) -- 2.7.4
