diff options
Diffstat (limited to 'Documentation/perf/qcom_l3_pmu.txt')
| -rw-r--r-- | Documentation/perf/qcom_l3_pmu.txt | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/perf/qcom_l3_pmu.txt b/Documentation/perf/qcom_l3_pmu.txt new file mode 100644 index 000000000000..96b3a9444a0d --- /dev/null +++ b/Documentation/perf/qcom_l3_pmu.txt @@ -0,0 +1,25 @@ +Qualcomm Datacenter Technologies L3 Cache Performance Monitoring Unit (PMU) +=========================================================================== + +This driver supports the L3 cache PMUs found in Qualcomm Datacenter Technologies +Centriq SoCs. The L3 cache on these SOCs is composed of multiple slices, shared +by all cores within a socket. Each slice is exposed as a separate uncore perf +PMU with device name l3cache_<socket>_<instance>. User space is responsible +for aggregating across slices. + +The driver provides a description of its available events and configuration +options in sysfs, see /sys/devices/l3cache*. Given that these are uncore PMUs +the driver also exposes a "cpumask" sysfs attribute which contains a mask +consisting of one CPU per socket which will be used to handle all the PMU +events on that socket. + +The hardware implements 32bit event counters and has a flat 8bit event space +exposed via the "event" format attribute. In addition to the 32bit physical +counters the driver supports virtual 64bit hardware counters by using hardware +counter chaining. This feature is exposed via the "lc" (long counter) format +flag. E.g.: + + perf stat -e l3cache_0_0/read-miss,lc/ + +Given that these are uncore PMUs the driver does not support sampling, therefore +"perf record" will not work. Per-task perf sessions are not supported. |