By allowing modifiers on metrics we can, for example, gather the
same metric for kernel and user mode. On a SkylakeX with
TopDownL1 this gives:

  $ perf stat -M TopDownL1:u,TopDownL1:k -a sleep 2

   Performance counter stats for 'system wide':

         849,855,577    uops_issued.any:k         #     0.06 Bad_Speculation:k
                                                  #     0.51 Backend_Bound:k          (16.71%)
       1,995,257,996    cycles:k
                                                  # 7981031984.00 SLOTS:k
                                                  #     0.35 Frontend_Bound:k
                                                  #     0.08 Retiring:k               (16.71%)
       2,791,940,753    idq_uops_not_delivered.core:k                                 (16.71%)
         641,961,928    uops_retired.retire_slots:k                                   (16.71%)
          72,239,337    int_misc.recovery_cycles:k                                    (16.71%)
       2,294,413,647    uops_issued.any:u         #     0.04 Bad_Speculation:u
                                                  #     0.39 Backend_Bound:u          (16.78%)
       1,333,248,940    cycles:u
                                                  # 5332995760.00 SLOTS:u
                                                  #     0.16 Frontend_Bound:u
                                                  #     0.40 Retiring:u               (16.78%)
         858,517,081    idq_uops_not_delivered.core:u                                 (16.78%)
       2,153,789,582    uops_retired.retire_slots:u                                   (16.78%)
          19,373,627    int_misc.recovery_cycles:u                                    (16.78%)
          31,503,661    cpu_clk_unhalted.one_thread_active:k #     0.18 CoreIPC_SMT:k (16.73%)
         315,454,104    inst_retired.any:k        # 315454104.00 Instructions:k       (16.73%)
          42,533,729    cpu_clk_unhalted.ref_xclk:k                                   (16.73%)
       2,043,119,037    cpu_clk_unhalted.thread:k                                     (16.73%)
          28,843,803    cpu_clk_unhalted.one_thread_active:u #     1.55 CoreIPC_SMT:u (16.60%)
       2,153,353,869    inst_retired.any:u        # 2153353869.00 Instructions:u      (16.60%)
          28,844,743    cpu_clk_unhalted.ref_xclk:u                                   (16.60%)
       1,387,544,378    cpu_clk_unhalted.thread:u                                     (16.60%)
         308,031,603    inst_retired.any:k        #     0.15 CoreIPC:k                (33.19%)
       2,036,774,753    cycles:k                                                      (33.19%)
       1,994,344,281    inst_retired.any:u        #     1.59 CoreIPC:u                (33.18%)
       1,251,538,227    cycles:u                                                      (33.18%)

         2.000342948 seconds time elapsed

Modifiers are naively copy and pasted on to events, this can yield errors like:

  $ perf stat -M Kernel_Utilization:k -a sleep 2
  event syntax error: '..d.thread:k/kk,cpu_clk_unhalted.thread/metric-id=cpu_clk_unhalted.thread/k..'
                                    \___ Bad modifier

   Usage: perf stat [<options>] [<command>]

      -M, --metrics <metric/metric group list>
                            monitor specified metrics or metric groups (separated by ,)

When modifiers are present with constraints, from --metric-no-group or
the NMI watchdog, they are no longer placed in the same set - which may
miss deduplicating events.
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Antonov <alexander.antonov@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrew Kilroy <andrew.kilroy@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Changbin Du <changbin.du@intel.com>
Cc: Denys Zagorui <dzagorui@cisco.com>
Cc: Fabian Hemmer <copy@copy.sh>
Cc: Felix Fietkau <nbd@nbd.name>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jacob Keller <jacob.e.keller@intel.com>
Cc: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joakim Zhang <qiangqing.zhang@nxp.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kees Kook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nicholas Fraser <nfraser@codeweavers.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Riccardo Mancini <rickyman7@gmail.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: ShihCheng Tu <mrtoastcheng@gmail.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Wan Jiabing <wanjiabing@vivo.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20211015172132.1162559-22-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>