perf stat: Combine the -A/--no-aggr and --no-merge options

The -A or --no-aggr option disables aggregation of core events:

  $ perf stat -A -e cycles,data_total -a true

   Performance counter stats for 'system wide':

  CPU0            1,287,665      cycles
  CPU1            1,831,681      cycles
  CPU2           27,345,998      cycles
  CPU3            1,964,799      cycles
  CPU4              236,174      cycles
  CPU5            3,302,825      cycles
  CPU6            9,201,446      cycles
  CPU7            1,403,043      cycles
  CPU0               110.90 MiB  data_total

         0.008961761 seconds time elapsed

The --no-merge option disables the aggregation of uncore events:

  $ perf stat --no-merge -e cycles,data_total -a true

   Performance counter stats for 'system wide':

          38,482,778      cycles
               15.04 MiB  data_total [uncore_imc_free_running_1]
               15.00 MiB  data_total [uncore_imc_free_running_0]

         0.005915155 seconds time elapsed

Having two options confuses users who generally don't appreciate the
difference in PMUs. Keep all the options but make it so they all
disable aggregation both of core and uncore events:

  $ perf stat -A -e cycles,data_total -a true

   Performance counter stats for 'system wide':

  CPU0               85,878      cycles
  CPU1               88,179      cycles
  CPU2               60,872      cycles
  CPU3            3,265,567      cycles
  CPU4               82,357      cycles
  CPU5               83,383      cycles
  CPU6               84,156      cycles
  CPU7              220,803      cycles
  CPU0                 2.38 MiB  data_total [uncore_imc_free_running_0]
  CPU0                 2.38 MiB  data_total [uncore_imc_free_running_1]

         0.001397205 seconds time elapsed

Update the relevant 'perf stat' man page information.

Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Kaige Ye <ye@kaige.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231214060256.2094017-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 28 insertions, 24 deletions

diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 8f789fa1242e..5af2e432b54f 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -422,7 +422,34 @@ See perf list output for the possible metrics and metricgroups.
 
 -A::
 --no-aggr::
-Do not aggregate counts across all monitored CPUs.
+--no-merge::
+Do not aggregate/merge counts across monitored CPUs or PMUs.
+
+When multiple events are created from a single event specification,
+stat will, by default, aggregate the event counts and show the result
+in a single row. This option disables that behavior and shows the
+individual events and counts.
+
+Multiple events are created from a single event specification when:
+
+1. PID monitoring isn't requested and the system has more than one
+   CPU. For example, a system with 8 SMT threads will have one event
+   opened on each thread and aggregation is performed across them.
+
+2. Prefix or glob wildcard matching is used for the PMU name. For
+   example, multiple memory controller PMUs may exist typically with a
+   suffix of _0, _1, etc. By default the event counts will all be
+   combined if the PMU is specified without the suffix such as
+   uncore_imc rather than uncore_imc_0.
+
+3. Aliases, which are listed immediately after the Kernel PMU events
+   by perf list, are used.
+
+--hybrid-merge::
+Merge core event counts from all core PMUs. In hybrid or big.LITTLE
+systems by default each core PMU will report its count
+separately. This option forces core PMU counts to be combined to give
+a behavior closer to having a single CPU type in the system.
 
 --topdown::
 Print top-down metrics supported by the CPU. This allows to determine
@@ -475,29 +502,6 @@ highlight 'tma_frontend_bound'. This metric may be drilled into with
 
 Error out if the input is higher than the supported max level.
 
---no-merge::
-Do not merge results from same PMUs.
-
-When multiple events are created from a single event specification,
-stat will, by default, aggregate the event counts and show the result
-in a single row. This option disables that behavior and shows
-the individual events and counts.
-
-Multiple events are created from a single event specification when:
-1. Prefix or glob matching is used for the PMU name.
-2. Aliases, which are listed immediately after the Kernel PMU events
-   by perf list, are used.
-
---hybrid-merge::
-Merge the hybrid event counts from all PMUs.
-
-For hybrid events, by default, the stat aggregates and reports the event
-counts per PMU. But sometimes, it's also useful to aggregate event counts
-from all PMUs. This option enables that behavior and reports the counts
-without PMUs.
-
-For non-hybrid events, it should be no effect.
-
 --smi-cost::
 Measure SMI cost if msr/aperf/ and msr/smi/ events are supported.