perf parse-events: Add 'X' modifier to exclude an event from being regrouped

The function parse_events__sort_events_and_fix_groups is needed to fix
uncore events like:
```
$ perf stat -e '{data_read,data_write}' ...
```
so that the multiple uncore PMUs have a group each of data_read and
data_write events.

The same function will perform architecture sorting and group fixing,
in particular for Intel topdown/perf-metric events. Grouping multiple
perf metric events together causes perf_event_open to fail as the
group can only support one. This means command lines like:
```
$ perf stat -e 'slots,slots' ...
```
fail as the slots events are forced into a group together to try to
satisfy the perf-metric event constraints.

As the user may know better than
parse_events__sort_events_and_fix_groups add a 'X' modifier to skip
its regrouping behavior. This allows the following to succeed rather
than fail on the second slots event being opened:
```
$ perf stat -e 'slots,slots:X' -a sleep 1

 Performance counter stats for 'system wide':

     6,834,154,071      cpu_core/slots/                                                         (50.13%)
     5,548,629,453      cpu_core/slots/X                                                        (49.87%)

       1.002634606 seconds time elapsed
```

Closes: https://lore.kernel.org/lkml/20250822082233.1850417-1-dapeng1.mi@linux.intel.com/
Reported-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Reported-by: Xudong Hao <xudong.hao@intel.com>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Falcon <thomas.falcon@intel.com>
Cc: Yoshihiro Furudera <fj5100bi@fujitsu.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/Documentation/perf-list.txt b/tools/perf/Documentation/perf-list.txt
index 28215306a78a482cef48aeb4546d1fa7c80b9b4c..a5039d1614f913f05265e9085d0e06df5354a879 100644 (file)
--- a/tools/perf/Documentation/perf-list.txt
+++ b/tools/perf/Documentation/perf-list.txt
@@ -73,6 +73,7 @@ counted. The following modifiers exist:
  e - group or event are exclusive and do not share the PMU
  b - use BPF aggregration (see perf stat --bpf-counters)
  R - retire latency value of the event
+ X - don't regroup the event to match PMUs
 
 The 'p' modifier can be used for specifying how precise the instruction
 address should be. The 'p' modifier can be specified multiple times:

diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index e927a3a4fe0e55c9af5b75aa34ac29490d89fec9..03f9f22e3a0cb480aef822a65102c600e6ffdc2e 100644 (file)
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -89,6 +89,7 @@ struct evsel {
                bool                    use_config_name;
                bool                    skippable;
                bool                    retire_lat;
+               bool                    dont_regroup;
                int                     bpf_fd;
                struct bpf_object       *bpf_obj;
                struct list_head        config_terms;

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 0026cff4d69e41503d10b739ea54acb0ceebbb1a..452f12191f6eb26134dd332b2d1b89d95909d17e 100644 (file)
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1896,6 +1896,8 @@ static int parse_events__modifier_list(struct parse_events_state *parse_state,
                        evsel->bpf_counter = true;
                if (mod.retire_lat)
                        evsel->retire_lat = true;
+               if (mod.dont_regroup)
+                       evsel->dont_regroup = true;
        }
        return 0;
 }
@@ -2192,13 +2194,12 @@ static int parse_events__sort_events_and_fix_groups(struct list_head *list)
                 * Set the group leader respecting the given groupings and that
                 * groups can't span PMUs.
                 */
-               if (!cur_leader) {
+               if (!cur_leader || pos->dont_regroup) {
                        cur_leader = pos;
                        cur_leaders_grp = &pos->core;
                        if (pos_force_grouped)
                                force_grouped_leader = pos;
                }
-
                cur_leader_pmu_name = cur_leader->group_pmu_name;
                if (strcmp(cur_leader_pmu_name, pos_pmu_name)) {
                        /* PMU changed so the group/leader must change. */

diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index 62dc7202e3bad5c31e28da4a657fbb186cda8502..a5c5fc39fd6fb98bbf833a9cc52578ffd00b5a19 100644 (file)
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -216,6 +216,7 @@ struct parse_events_modifier {
        bool guest : 1;         /* 'G' */
        bool host : 1;          /* 'H' */
        bool retire_lat : 1;    /* 'R' */
+       bool dont_regroup : 1;  /* 'X' */
 };
 
 int parse_events__modifier_event(struct parse_events_state *parse_state, void *loc,

diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
index 2034590eb7893db25bcb246f41db4e8e528271bc..294e943bcdb448c0ff0676a167a06d80faeafb0a 100644 (file)
--- a/tools/perf/util/parse-events.l
+++ b/tools/perf/util/parse-events.l
@@ -206,6 +206,7 @@ static int modifiers(struct parse_events_state *parse_state, yyscan_t scanner)
                CASE('e', exclusive);
                CASE('b', bpf);
                CASE('R', retire_lat);
+               CASE('X', dont_regroup);
                default:
                        return PE_ERROR;
                }
@@ -251,10 +252,10 @@ term_name {name_start}[a-zA-Z0-9_*?.\[\]!\-:]*
 quoted_name    [\']{name_start}[a-zA-Z0-9_*?.\[\]!\-:,\.=]*[\']
 drv_cfg_term   [a-zA-Z0-9_\.]+(=[a-zA-Z0-9_*?\.:]+)?
 /*
- * If you add a modifier you need to update check_modifier().
+ * If you add a modifier you need to update modifiers().
  * Also, the letters in modifier_event must not be in modifier_bp.
  */
-modifier_event [ukhpPGHSDIWebR]{1,16}
+modifier_event [ukhpPGHSDIWebRX]{1,17}
 modifier_bp    [rwx]{1,3}
 lc_type        (L1-dcache|l1-d|l1d|L1-data|L1-icache|l1-i|l1i|L1-instruction|LLC|L2|dTLB|d-tlb|Data-TLB|iTLB|i-tlb|Instruction-TLB|branch|branches|bpu|btb|bpc|node)
 lc_op_result   (load|loads|read|store|stores|write|prefetch|prefetches|speculative-read|speculative-load|refs|Reference|ops|access|misses|miss)