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 <[e-mail]>
Signed-off-by: Ian Rogers <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Athira Jajeev <[e-mail]>
Cc: Changbin Du <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Clark <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: John Garry <[e-mail]>
Cc: K Prateek Nayak <[e-mail]>
Cc: Kaige Ye <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Nick Desaulniers <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Documentation/perf-stat.txt

···
 
 -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
···
 'perf stat -M tma_frontend_bound_group...'.
 
 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.

tools/perf/builtin-stat.c

···
 	OPT_STRING('C', "cpu", &target.cpu_list, "cpu",
 		    "list of cpus to monitor in system-wide"),
 	OPT_SET_UINT('A', "no-aggr", &stat_config.aggr_mode,
-		    "disable CPU count aggregation", AGGR_NONE),
-	OPT_BOOLEAN(0, "no-merge", &stat_config.no_merge, "Do not merge identical named events"),
+		    "disable aggregation across CPUs or PMUs", AGGR_NONE),
+	OPT_SET_UINT(0, "no-merge", &stat_config.aggr_mode,
+		    "disable aggregation the same as -A or -no-aggr", AGGR_NONE),
 	OPT_BOOLEAN(0, "hybrid-merge", &stat_config.hybrid_merge,
 		    "Merge identical named hybrid events"),
 	OPT_STRING('x', "field-separator", &stat_config.csv_sep, "separator",

tools/perf/util/stat-display.c

···
 
 static void uniquify_counter(struct perf_stat_config *config, struct evsel *counter)
 {
-	if (config->no_merge || hybrid_uniquify(counter, config))
+	if (config->aggr_mode == AGGR_NONE || hybrid_uniquify(counter, config))
 		uniquify_event_name(counter);
 }
 

tools/perf/util/stat.c

···
 {
 	struct evsel *evsel;
 
-	if (config->no_merge)
+	if (config->aggr_mode == AGGR_NONE)
 		return;
 
 	evlist__for_each_entry(evlist, evsel)

tools/perf/util/stat.h

···
 	bool			 null_run;
 	bool			 ru_display;
 	bool			 big_num;
-	bool			 no_merge;
 	bool			 hybrid_merge;
 	bool			 walltime_run_table;
 	bool			 all_kernel;