docs: perf: move to the admin-guide

The perf infrastructure is used for userspace to track issues.
At least a good part of what's described here is related to
it.

So, add it to the admin-guide.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

9 files changed, 321 insertions, 0 deletions

diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst
index 8853c95ef0d4..f40c4b5a181b 100644
--- a/Documentation/admin-guide/index.rst
+++ b/Documentation/admin-guide/index.rst
@@ -38,6 +38,7 @@ problems and bugs in particular.
    ramoops
    dynamic-debug-howto
    init
+   perf/index
 
 This is the beginning of a section with information of interest to
 application developers.  Documents covering various aspects of the kernel
diff --git a/Documentation/admin-guide/perf/arm-ccn.rst b/Documentation/admin-guide/perf/arm-ccn.rst
new file mode 100644
index 000000000000..832b0c64023a
--- /dev/null
+++ b/Documentation/admin-guide/perf/arm-ccn.rst
@@ -0,0 +1,61 @@
+==========================
+ARM Cache Coherent Network
+==========================
+
+CCN-504 is a ring-bus interconnect consisting of 11 crosspoints
+(XPs), with each crosspoint supporting up to two device ports,
+so nodes (devices) 0 and 1 are connected to crosspoint 0,
+nodes 2 and 3 to crosspoint 1 etc.
+
+PMU (perf) driver
+-----------------
+
+The CCN driver registers a perf PMU driver, which provides
+description of available events and configuration options
+in sysfs, see /sys/bus/event_source/devices/ccn*.
+
+The "format" directory describes format of the config, config1
+and config2 fields of the perf_event_attr structure. The "events"
+directory provides configuration templates for all documented
+events, that can be used with perf tool. For example "xp_valid_flit"
+is an equivalent of "type=0x8,event=0x4". Other parameters must be
+explicitly specified.
+
+For events originating from device, "node" defines its index.
+
+Crosspoint PMU events require "xp" (index), "bus" (bus number)
+and "vc" (virtual channel ID).
+
+Crosspoint watchpoint-based events (special "event" value 0xfe)
+require "xp" and "vc" as as above plus "port" (device port index),
+"dir" (transmit/receive direction), comparator values ("cmp_l"
+and "cmp_h") and "mask", being index of the comparator mask.
+
+Masks are defined separately from the event description
+(due to limited number of the config values) in the "cmp_mask"
+directory, with first 8 configurable by user and additional
+4 hardcoded for the most frequent use cases.
+
+Cycle counter is described by a "type" value 0xff and does
+not require any other settings.
+
+The driver also provides a "cpumask" sysfs attribute, which contains
+a single CPU ID, of the processor which will be used to handle all
+the CCN PMU events. It is recommended that the user space tools
+request the events on this processor (if not, the perf_event->cpu value
+will be overwritten anyway). In case of this processor being offlined,
+the events are migrated to another one and the attribute is updated.
+
+Example of perf tool use::
+
+  / # perf list | grep ccn
+    ccn/cycles/                                        [Kernel PMU event]
+  <...>
+    ccn/xp_valid_flit,xp=?,port=?,vc=?,dir=?/          [Kernel PMU event]
+  <...>
+
+  / # perf stat -a -e ccn/cycles/,ccn/xp_valid_flit,xp=1,port=0,vc=1,dir=1/ \
+                                                                         sleep 1
+
+The driver does not support sampling, therefore "perf record" will
+not work. Per-task (without "-a") perf sessions are not supported.
diff --git a/Documentation/admin-guide/perf/arm_dsu_pmu.rst b/Documentation/admin-guide/perf/arm_dsu_pmu.rst
new file mode 100644
index 000000000000..7fd34db75d13
--- /dev/null
+++ b/Documentation/admin-guide/perf/arm_dsu_pmu.rst
@@ -0,0 +1,29 @@
+==================================
+ARM DynamIQ Shared Unit (DSU) PMU
+==================================
+
+ARM DynamIQ Shared Unit integrates one or more cores with an L3 memory system,
+control logic and external interfaces to form a multicore cluster. The PMU
+allows counting the various events related to the L3 cache, Snoop Control Unit
+etc, using 32bit independent counters. It also provides a 64bit cycle counter.
+
+The PMU can only be accessed via CPU system registers and are common to the
+cores connected to the same DSU. Like most of the other uncore PMUs, DSU
+PMU doesn't support process specific events and cannot be used in sampling mode.
+
+The DSU provides a bitmap for a subset of implemented events via hardware
+registers. There is no way for the driver to determine if the other events
+are available or not. Hence the driver exposes only those events advertised
+by the DSU, in "events" directory under::
+
+  /sys/bus/event_sources/devices/arm_dsu_<N>/
+
+The user should refer to the TRM of the product to figure out the supported events
+and use the raw event code for the unlisted events.
+
+The driver also exposes the CPUs connected to the DSU instance in "associated_cpus".
+
+
+e.g usage::
+
+	perf stat -a -e arm_dsu_0/cycles/
diff --git a/Documentation/admin-guide/perf/hisi-pmu.rst b/Documentation/admin-guide/perf/hisi-pmu.rst
new file mode 100644
index 000000000000..404a5c3d9d00
--- /dev/null
+++ b/Documentation/admin-guide/perf/hisi-pmu.rst
@@ -0,0 +1,60 @@
+======================================================
+HiSilicon SoC uncore Performance Monitoring Unit (PMU)
+======================================================
+
+The HiSilicon SoC chip includes various independent system device PMUs
+such as L3 cache (L3C), Hydra Home Agent (HHA) and DDRC. These PMUs are
+independent and have hardware logic to gather statistics and performance
+information.
+
+The HiSilicon SoC encapsulates multiple CPU and IO dies. Each CPU cluster
+(CCL) is made up of 4 cpu cores sharing one L3 cache; each CPU die is
+called Super CPU cluster (SCCL) and is made up of 6 CCLs. Each SCCL has
+two HHAs (0 - 1) and four DDRCs (0 - 3), respectively.
+
+HiSilicon SoC uncore PMU driver
+-------------------------------
+
+Each device PMU has separate registers for event counting, control and
+interrupt, and the PMU driver shall register perf PMU drivers like L3C,
+HHA and DDRC etc. The available events and configuration options shall
+be described in the sysfs, see:
+
+/sys/devices/hisi_sccl{X}_<l3c{Y}/hha{Y}/ddrc{Y}>/, or
+/sys/bus/event_source/devices/hisi_sccl{X}_<l3c{Y}/hha{Y}/ddrc{Y}>.
+The "perf list" command shall list the available events from sysfs.
+
+Each L3C, HHA and DDRC is registered as a separate PMU with perf. The PMU
+name will appear in event listing as hisi_sccl<sccl-id>_module<index-id>.
+where "sccl-id" is the identifier of the SCCL and "index-id" is the index of
+module.
+
+e.g. hisi_sccl3_l3c0/rd_hit_cpipe is READ_HIT_CPIPE event of L3C index #0 in
+SCCL ID #3.
+
+e.g. hisi_sccl1_hha0/rx_operations is RX_OPERATIONS event of HHA index #0 in
+SCCL ID #1.
+
+The driver also provides a "cpumask" sysfs attribute, which shows the CPU core
+ID used to count the uncore PMU event.
+
+Example usage of perf::
+
+  $# perf list
+  hisi_sccl3_l3c0/rd_hit_cpipe/ [kernel PMU event]
+  ------------------------------------------
+  hisi_sccl3_l3c0/wr_hit_cpipe/ [kernel PMU event]
+  ------------------------------------------
+  hisi_sccl1_l3c0/rd_hit_cpipe/ [kernel PMU event]
+  ------------------------------------------
+  hisi_sccl1_l3c0/wr_hit_cpipe/ [kernel PMU event]
+  ------------------------------------------
+
+  $# perf stat -a -e hisi_sccl3_l3c0/rd_hit_cpipe/ sleep 5
+  $# perf stat -a -e hisi_sccl3_l3c0/config=0x02/ sleep 5
+
+The current driver does not support sampling. So "perf record" is unsupported.
+Also attach to a task is unsupported as the events are all uncore.
+
+Note: Please contact the maintainer for a complete list of events supported for
+the PMU devices in the SoC and its information if needed.
diff --git a/Documentation/admin-guide/perf/index.rst b/Documentation/admin-guide/perf/index.rst
new file mode 100644
index 000000000000..9d445451ea18
--- /dev/null
+++ b/Documentation/admin-guide/perf/index.rst
@@ -0,0 +1,14 @@
+===========================
+Performance monitor support
+===========================
+
+.. toctree::
+   :maxdepth: 1
+
+   hisi-pmu
+   qcom_l2_pmu
+   qcom_l3_pmu
+   arm-ccn
+   xgene-pmu
+   arm_dsu_pmu
+   thunderx2-pmu
diff --git a/Documentation/admin-guide/perf/qcom_l2_pmu.rst b/Documentation/admin-guide/perf/qcom_l2_pmu.rst
new file mode 100644
index 000000000000..c130178a4a55
--- /dev/null
+++ b/Documentation/admin-guide/perf/qcom_l2_pmu.rst
@@ -0,0 +1,39 @@
+=====================================================================
+Qualcomm Technologies Level-2 Cache Performance Monitoring Unit (PMU)
+=====================================================================
+
+This driver supports the L2 cache clusters found in Qualcomm Technologies
+Centriq SoCs. There are multiple physical L2 cache clusters, each with their
+own PMU. Each cluster has one or more CPUs associated with it.
+
+There is one logical L2 PMU exposed, which aggregates the results from
+the physical PMUs.
+
+The driver provides a description of its available events and configuration
+options in sysfs, see /sys/devices/l2cache_0.
+
+The "format" directory describes the format of the events.
+
+Events can be envisioned as a 2-dimensional array. Each column represents
+a group of events. There are 8 groups. Only one entry from each
+group can be in use at a time. If multiple events from the same group
+are specified, the conflicting events cannot be counted at the same time.
+
+Events are specified as 0xCCG, where CC is 2 hex digits specifying
+the code (array row) and G specifies the group (column) 0-7.
+
+In addition there is a cycle counter event specified by the value 0xFE
+which is outside the above scheme.
+
+The driver provides a "cpumask" sysfs attribute which contains a mask
+consisting of one CPU per cluster which will be used to handle all the PMU
+events on that cluster.
+
+Examples for use with perf::
+
+  perf stat -e l2cache_0/config=0x001/,l2cache_0/config=0x042/ -a sleep 1
+
+  perf stat -e l2cache_0/config=0xfe/ -C 2 sleep 1
+
+The driver does not support sampling, therefore "perf record" will
+not work. Per-task perf sessions are not supported.
diff --git a/Documentation/admin-guide/perf/qcom_l3_pmu.rst b/Documentation/admin-guide/perf/qcom_l3_pmu.rst
new file mode 100644
index 000000000000..a3d014a46bfd
--- /dev/null
+++ b/Documentation/admin-guide/perf/qcom_l3_pmu.rst
@@ -0,0 +1,26 @@
+===========================================================================
+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.
diff --git a/Documentation/admin-guide/perf/thunderx2-pmu.rst b/Documentation/admin-guide/perf/thunderx2-pmu.rst
new file mode 100644
index 000000000000..08e33675853a
--- /dev/null
+++ b/Documentation/admin-guide/perf/thunderx2-pmu.rst
@@ -0,0 +1,42 @@
+=============================================================
+Cavium ThunderX2 SoC Performance Monitoring Unit (PMU UNCORE)
+=============================================================
+
+The ThunderX2 SoC PMU consists of independent, system-wide, per-socket
+PMUs such as the Level 3 Cache (L3C) and DDR4 Memory Controller (DMC).
+
+The DMC has 8 interleaved channels and the L3C has 16 interleaved tiles.
+Events are counted for the default channel (i.e. channel 0) and prorated
+to the total number of channels/tiles.
+
+The DMC and L3C support up to 4 counters. Counters are independently
+programmable and can be started and stopped individually. Each counter
+can be set to a different event. Counters are 32-bit and do not support
+an overflow interrupt; they are read every 2 seconds.
+
+PMU UNCORE (perf) driver:
+
+The thunderx2_pmu driver registers per-socket perf PMUs for the DMC and
+L3C devices.  Each PMU can be used to count up to 4 events
+simultaneously. The PMUs provide a description of their available events
+and configuration options under sysfs, see
+/sys/devices/uncore_<l3c_S/dmc_S/>; S is the socket id.
+
+The driver does not support sampling, therefore "perf record" will not
+work. Per-task perf sessions are also not supported.
+
+Examples::
+
+  # perf stat -a -e uncore_dmc_0/cnt_cycles/ sleep 1
+
+  # perf stat -a -e \
+  uncore_dmc_0/cnt_cycles/,\
+  uncore_dmc_0/data_transfers/,\
+  uncore_dmc_0/read_txns/,\
+  uncore_dmc_0/write_txns/ sleep 1
+
+  # perf stat -a -e \
+  uncore_l3c_0/read_request/,\
+  uncore_l3c_0/read_hit/,\
+  uncore_l3c_0/inv_request/,\
+  uncore_l3c_0/inv_hit/ sleep 1
diff --git a/Documentation/admin-guide/perf/xgene-pmu.rst b/Documentation/admin-guide/perf/xgene-pmu.rst
new file mode 100644
index 000000000000..644f8ed89152
--- /dev/null
+++ b/Documentation/admin-guide/perf/xgene-pmu.rst
@@ -0,0 +1,49 @@
+================================================
+APM X-Gene SoC Performance Monitoring Unit (PMU)
+================================================
+
+X-Gene SoC PMU consists of various independent system device PMUs such as
+L3 cache(s), I/O bridge(s), memory controller bridge(s) and memory
+controller(s). These PMU devices are loosely architected to follow the
+same model as the PMU for ARM cores. The PMUs share the same top level
+interrupt and status CSR region.
+
+PMU (perf) driver
+-----------------
+
+The xgene-pmu driver registers several perf PMU drivers. Each of the perf
+driver provides description of its available events and configuration options
+in sysfs, see /sys/devices/<l3cX/iobX/mcbX/mcX>/.
+
+The "format" directory describes format of the config (event ID),
+config1 (agent ID) fields of the perf_event_attr structure. The "events"
+directory provides configuration templates for all supported event types that
+can be used with perf tool. For example, "l3c0/bank-fifo-full/" is an
+equivalent of "l3c0/config=0x0b/".
+
+Most of the SoC PMU has a specific list of agent ID used for monitoring
+performance of a specific datapath. For example, agents of a L3 cache can be
+a specific CPU or an I/O bridge. Each PMU has a set of 2 registers capable of
+masking the agents from which the request come from. If the bit with
+the bit number corresponding to the agent is set, the event is counted only if
+it is caused by a request from that agent. Each agent ID bit is inversely mapped
+to a corresponding bit in "config1" field. By default, the event will be
+counted for all agent requests (config1 = 0x0). For all the supported agents of
+each PMU, please refer to APM X-Gene User Manual.
+
+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.
+
+Example for perf tool use::
+
+ / # perf list | grep -e l3c -e iob -e mcb -e mc
+   l3c0/ackq-full/                                    [Kernel PMU event]
+ <...>
+   mcb1/mcb-csw-stall/                                [Kernel PMU event]
+
+ / # perf stat -a -e l3c0/read-miss/,mcb1/csw-write-request/ sleep 1
+
+ / # perf stat -a -e l3c0/read-miss,config1=0xfffffffffffffffe/ sleep 1
+
+The driver does not support sampling, therefore "perf record" will
+not work. Per-task (without "-a") perf sessions are not supported.