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Subject[RESEND PATCH 1/2] perf: uncore: Adding documentation for ThunderX2 pmu uncore driver
Date
Documentation for the UNCORE PMUs on Cavium's ThunderX2 SoC.
The SoC has PMU support in its L3 cache controller (L3C) and in the
DDR4 Memory Controller (DMC).

Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
---
Documentation/perf/thunderx2-pmu.txt | 60 ++++++++++++++++++++++++++++++++++++
1 file changed, 60 insertions(+)
create mode 100644 Documentation/perf/thunderx2-pmu.txt

diff --git a/Documentation/perf/thunderx2-pmu.txt b/Documentation/perf/thunderx2-pmu.txt
new file mode 100644
index 0000000..eb8df9a
--- /dev/null
+++ b/Documentation/perf/thunderx2-pmu.txt
@@ -0,0 +1,60 @@
+
+Cavium ThunderX2 SoC Performance Monitoring Unit (PMU UNCORE)
+=============================================================
+
+ThunderX2 SoC PMU consists of independent system wide PMUs such as
+Level 3 Cache(L3C) and DDR4 Memory Controller(DMC).
+
+DMC: There are 8 independent PMUs to capture performance events corresponding
+to 8 channels of DDR4 Memory Controller. Each PMU supports upto 4 counters.
+
+L3C: There are 16 independent PMUs to capture events corresponding to 16 tiles
+of L3 cache. Each PMU supports up to 4 counters.
+
+PMU UNCORE (perf) driver
+-----------------------
+
+The thunderx2-pmu driver registers several perf PMUs for DMC and L3C devices.
+Each of the PMU provides description of its available events
+and configuration options in sysfs.
+ see /sys/devices/uncore_<l3c_X/dmc_S_X/.
+
+S is socket id and X represents channel number.
+There are 8 supported channels for DMC and 16 for L3C.
+Each channel supports up to 4 counters, which can be measured
+simultaneously without event muxing for each channel.
+
+The "format" directory describes format of the config (event ID).
+The "events" directory provides configuration templates for all
+supported event types that can be used with perf tool.
+
+For example, "uncore_dmc_0_0/cnt_cycles/" is an
+equivalent of "uncore_dmc_0_0/config=0x1/".
+
+
+Each perf driver also provides a "cpumask" sysfs attribute, which contains a
+single CPU ID of the processor which will be used to handle all the PMU events.
+It will be the first online CPU of the node of PMU device.
+
+Example for perf tool use:
+
+perf stat -a -e \
+ uncore_dmc_0_0/cnt_cycles/,\
+ uncore_dmc_0_1/cnt_cycles/,\
+ uncore_dmc_0_2/cnt_cycles/,\
+ uncore_dmc_0_3/cnt_cycles/,\
+ uncore_dmc_0_4/cnt_cycles/,\
+ uncore_dmc_0_5/cnt_cycles/,\
+ uncore_dmc_0_6/cnt_cycles/,\
+ uncore_dmc_0_7/cnt_cycles/ \
+ sleep 1
+
+perf stat -a -e \
+ uncore_dmc_0_0/cnt_cycles/,\
+ uncore_dmc_0_0/data_txfered/,\
+ uncore_dmc_0_0/txn_cycles/,\
+ uncore_dmc_0_0/cancelled_read_txn/ \
+ sleep 1
+
+The driver does not support sampling, therefore "perf record" will
+not work. Per-task (without "-a") perf sessions are not supported.
--
1.8.1.4
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