]> git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - Documentation/perf/qcom_l2_pmu.txt
Merge tag 'pm-turbostat-4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git...
[mirror_ubuntu-artful-kernel.git] / Documentation / perf / qcom_l2_pmu.txt
1 Qualcomm Technologies Level-2 Cache Performance Monitoring Unit (PMU)
2 =====================================================================
3
4 This driver supports the L2 cache clusters found in Qualcomm Technologies
5 Centriq SoCs. There are multiple physical L2 cache clusters, each with their
6 own PMU. Each cluster has one or more CPUs associated with it.
7
8 There is one logical L2 PMU exposed, which aggregates the results from
9 the physical PMUs.
10
11 The driver provides a description of its available events and configuration
12 options in sysfs, see /sys/devices/l2cache_0.
13
14 The "format" directory describes the format of the events.
15
16 Events can be envisioned as a 2-dimensional array. Each column represents
17 a group of events. There are 8 groups. Only one entry from each
18 group can be in use at a time. If multiple events from the same group
19 are specified, the conflicting events cannot be counted at the same time.
20
21 Events are specified as 0xCCG, where CC is 2 hex digits specifying
22 the code (array row) and G specifies the group (column) 0-7.
23
24 In addition there is a cycle counter event specified by the value 0xFE
25 which is outside the above scheme.
26
27 The driver provides a "cpumask" sysfs attribute which contains a mask
28 consisting of one CPU per cluster which will be used to handle all the PMU
29 events on that cluster.
30
31 Examples for use with perf:
32
33 perf stat -e l2cache_0/config=0x001/,l2cache_0/config=0x042/ -a sleep 1
34
35 perf stat -e l2cache_0/config=0xfe/ -C 2 sleep 1
36
37 The driver does not support sampling, therefore "perf record" will
38 not work. Per-task perf sessions are not supported.