perf stat: Enable iostat mode for x86 platforms

This functionality is based on recently introduced sysfs attributes for
Intel® Xeon® Scalable processor family (code name Skylake-SP):

Commit bb42b3d39781d7fc ("perf/x86/intel/uncore: Expose an Uncore unit to IIO PMON mapping")

Mode is intended to provide four I/O performance metrics in MB per each
PCIe root port:

 - Inbound Read: I/O devices below root port read from the host memory
 - Inbound Write: I/O devices below root port write to the host memory
 - Outbound Read: CPU reads from I/O devices below root port
 - Outbound Write: CPU writes to I/O devices below root port

Each metric requiries only one uncore event which increments at every 4B
transfer in corresponding direction. The formulas to compute metrics
are generic:
    #EventCount * 4B / (1024 * 1024)

Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Alexander Antonov <alexander.antonov@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey V Bayduraev <alexey.v.bayduraev@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210419094147.15909-4-alexander.antonov@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 88 insertions, 0 deletions

diff --git a/tools/perf/Documentation/perf-iostat.txt b/tools/perf/Documentation/perf-iostat.txt
new file mode 100644
index 000000000000..165176944031
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+++ b/tools/perf/Documentation/perf-iostat.txt
@@ -0,0 +1,88 @@
+perf-iostat(1)
+===============
+
+NAME
+----
+perf-iostat - Show I/O performance metrics
+
+SYNOPSIS
+--------
+[verse]
+'perf iostat' list
+'perf iostat' <ports> -- <command> [<options>]
+
+DESCRIPTION
+-----------
+Mode is intended to provide four I/O performance metrics per each PCIe root port:
+
+- Inbound Read   - I/O devices below root port read from the host memory, in MB
+
+- Inbound Write  - I/O devices below root port write to the host memory, in MB
+
+- Outbound Read  - CPU reads from I/O devices below root port, in MB
+
+- Outbound Write - CPU writes to I/O devices below root port, in MB
+
+OPTIONS
+-------
+<command>...::
+	Any command you can specify in a shell.
+
+list::
+	List all PCIe root ports.
+
+<ports>::
+	Select the root ports for monitoring. Comma-separated list is supported.
+
+EXAMPLES
+--------
+
+1. List all PCIe root ports (example for 2-S platform):
+
+   $ perf iostat list
+   S0-uncore_iio_0<0000:00>
+   S1-uncore_iio_0<0000:80>
+   S0-uncore_iio_1<0000:17>
+   S1-uncore_iio_1<0000:85>
+   S0-uncore_iio_2<0000:3a>
+   S1-uncore_iio_2<0000:ae>
+   S0-uncore_iio_3<0000:5d>
+   S1-uncore_iio_3<0000:d7>
+
+2. Collect metrics for all PCIe root ports:
+
+   $ perf iostat -- dd if=/dev/zero of=/dev/nvme0n1 bs=1M oflag=direct
+   357708+0 records in
+   357707+0 records out
+   375083606016 bytes (375 GB, 349 GiB) copied, 215.974 s, 1.7 GB/s
+
+    Performance counter stats for 'system wide':
+
+      port             Inbound Read(MB)    Inbound Write(MB)    Outbound Read(MB)   Outbound Write(MB)
+   0000:00                    1                    0                    2                    3
+   0000:80                    0                    0                    0                    0
+   0000:17               352552                   43                    0                   21
+   0000:85                    0                    0                    0                    0
+   0000:3a                    3                    0                    0                    0
+   0000:ae                    0                    0                    0                    0
+   0000:5d                    0                    0                    0                    0
+   0000:d7                    0                    0                    0                    0
+
+3. Collect metrics for comma-separated list of PCIe root ports:
+
+   $ perf iostat 0000:17,0:3a -- dd if=/dev/zero of=/dev/nvme0n1 bs=1M oflag=direct
+   357708+0 records in
+   357707+0 records out
+   375083606016 bytes (375 GB, 349 GiB) copied, 197.08 s, 1.9 GB/s
+
+    Performance counter stats for 'system wide':
+
+      port             Inbound Read(MB)    Inbound Write(MB)    Outbound Read(MB)   Outbound Write(MB)
+   0000:17               358559                   44                    0                   22
+   0000:3a                    3                    2                    0                    0
+
+        197.081983474 seconds time elapsed
+
+SEE ALSO
+--------
+linkperf:perf-stat[1]
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