[RFC PATCH v2 8/9] perf docs: Add perf-sysinfo man page

[Ian Rogers <irogers@google.com>]

Document the 'perf sysinfo' subcommand and its options in
Documentation/perf-sysinfo.txt and link it from Documentation/perf.txt.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/Documentation/perf-sysinfo.txt | 109 ++++++++++++++++++++++
 tools/perf/Documentation/perf.txt         |   2 +-
 2 files changed, 110 insertions(+), 1 deletion(-)
 create mode 100644 tools/perf/Documentation/perf-sysinfo.txt

diff --git a/tools/perf/Documentation/perf-sysinfo.txt b/tools/perf/Documentation/perf-sysinfo.txt
new file mode 100644
index 000000000000..4fc5fe229060
--- /dev/null
+++ b/tools/perf/Documentation/perf-sysinfo.txt
@@ -0,0 +1,109 @@
+perf-sysinfo(1)
+===============
+
+NAME
+----
+perf-sysinfo - Display and probe PMU and system performance monitoring information
+
+SYNOPSIS
+--------
+[verse]
+'perf sysinfo' [<options>] [pmu_glob ...]
+
+DESCRIPTION
+-----------
+This command displays a summary of the performance monitoring capabilities of
+the current system or a perf.data file, including core PMU features (precise
+sampling, branch stack sampling, user-space counter reading, memory profiling,
+and hardware AUX trace PMUs), memory and PCIe/IO interconnect bus bandwidth
+monitoring support, total events and metrics, pipeline metric drill-down levels
+discovered via '<metric>_group' hierarchies, and an overall system rating.
+
+When '-p'/'--pmus' is specified (or when PMU filter globs, '-v'/'--verbose',
+'-a'/'--all', or '-j'/'--json' are given), it also displays detailed
+information for each PMU, including its perf_event_attr type, kind (core,
+uncore, software, auxtrace, tool, hwmon, drm), CPUs/cpumask, capabilities,
+sysfs format bitfields, event counts, and memory profiling events.
+
+When run on a live system (without '-i'/'--input' and with probing enabled),
+it also actively probes the kernel via 'perf_event_open' to determine:
+- Supported modes (counting, interrupt-based sampling, branch_stack sampling)
+- Supported precise sampling levels, skid semantics, and empirically measured
+  branch instruction skid (minimum, maximum, average instructions from the
+  branch and 'PERF_RECORD_MISC_EXACT_IP' ratio) at each supported precision
+  level:
+  0 ('SAMPLE_IP' can have arbitrary skid), ':p' / 1 ('SAMPLE_IP' must have
+  constant skid), ':pp' / 2 ('SAMPLE_IP' requested to have 0 skid), and
+  ':ppp' / 3 ('SAMPLE_IP' must have 0 skid, or uses randomization to avoid
+  sample shadowing effects)
+- Supported 'perf_event_sample_format' sample types ('ip', 'tid', 'time',
+  'addr', 'read', 'callchain', 'id', 'cpu', 'period', 'stream_id', 'raw',
+  'branch_stack', 'regs_user', 'stack_user', 'weight', 'data_src',
+  'identifier', 'transaction', 'regs_intr', 'phys_addr', 'aux', 'cgroup',
+  'data_page_size', 'code_page_size', 'weight_struct')
+- Supported user and interrupt registers for 'PERF_SAMPLE_REGS_USER' and
+  'PERF_SAMPLE_REGS_INTR'
+- Supported memory profiling events ('ldlat-loads', 'ldlat-stores', 'mem-ldst')
+  and their supported memory sample types ('data_src', 'addr', 'weight', etc.)
+- Supported privilege/exclusion modifiers ('exclude_user', 'exclude_kernel',
+  'exclude_hv', 'exclude_idle', 'exclude_host', 'exclude_guest')
+- Supported execution features ('leader_sampling', 'sw_grouping', 'inherit',
+  'sample_freq', 'write_backward', 'callchain', 'data_src', 'weight',
+  'pinned', 'exclusive', 'format_lost', 'auto_counter_reload',
+  'aux_start_paused', 'aux_pause', 'aux_resume', 'aux_sample', 'user_rdpmc',
+  'user_time', 'user_time_zero', 'user_time_short') and hardware counter
+  bit-width ('pmc_width') when user-space counter reading is supported
+- Maximum event group size accepted by 'perf_event_open' and maximum
+  simultaneously active counters in a group without multiplexing
+
+At the end of the text output, a summary section reports overall core PMU
+capabilities (including hardware AUX trace PMUs), memory and PCIe/IO
+interconnect bus bandwidth monitoring support, total events and metrics, and
+pipeline metric drill-down levels discovered via '<metric>_group' hierarchies.
+
+By default, numbered uncore PMU instances sharing a common prefix are collapsed
+into a single entry showing the instance count, unless '-v'/'--verbose' is
+specified.
+
+OPTIONS
+-------
+-i::
+--input=::
+	Input file name to read PMU information from (e.g. perf.data).
+
+-f::
+--force::
+	Don't complain, do it (when reading input perf.data file).
+
+-o::
+--output=::
+	Output file name.
+
+-p::
+--pmus::
+	Display detailed information for each PMU in addition to the system
+	summary.
+
+-j::
+--json::
+	Encode PMU information as JSON.
+
+-a::
+--all::
+-v::
+--verbose::
+	Display all PMUs including all similar PMUs with alphanumeric suffixes
+	instead of collapsing numbered uncore PMU instances.
+
+--probe::
+--no-probe::
+	Enable or disable active kernel probing of PMU capabilities on the live
+	system (default: enabled).
+
+--debug::
+	Enable debugging output.
+
+SEE ALSO
+--------
+linkperf:perf-list[1], linkperf:perf-evlist[1], linkperf:perf-stat[1],
+linkperf:perf-record[1]
diff --git a/tools/perf/Documentation/perf.txt b/tools/perf/Documentation/perf.txt
index cbcc2e4d557e..0890dd5a1794 100644
--- a/tools/perf/Documentation/perf.txt
+++ b/tools/perf/Documentation/perf.txt
@@ -92,5 +92,5 @@ linkperf:perf-help[1], linkperf:perf-inject[1],
 linkperf:perf-intel-pt[1], linkperf:perf-iostat[1], linkperf:perf-kallsyms[1],
 linkperf:perf-kmem[1], linkperf:perf-kvm[1], linkperf:perf-lock[1],
 linkperf:perf-mem[1], linkperf:perf-probe[1], linkperf:perf-sched[1],
-linkperf:perf-script[1], linkperf:perf-test[1],
+linkperf:perf-script[1], linkperf:perf-sysinfo[1], linkperf:perf-test[1],
 linkperf:perf-trace[1], linkperf:perf-version[1]
-- 
2.56.0.212.g129ede20d9-goog