This patch adds support for "--per-cache" option for aggregation at a
particular cache level and documents the same.

Following is the output of 'perf stat' with aggregation at L3 for the
event "ls_dmnd_fills_from_sys.ext_cache_remote" on a dual socket 3rd
Generation EPYC Processor (2 x 64C/128T - 16 LLCs) when running
hackbench pinned to 4 LLCs:

  $ sudo perf stat --per-cache=L3 -a -e ls_dmnd_fills_from_sys.ext_cache_remote -- \
    taskset -c 0-15,64-79,128-143,192-207 \
    perf bench sched messaging -p -t -l 100000 -g 8

  ...

   Performance counter stats for 'system wide':

  S0-D0-L3-ID0             16          9,500,803      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID8             16          6,338,099      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID16            16            355,005      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID24            16             22,067      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID32            16             16,321      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID40            16             11,619      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID48            16              4,238      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID56            16             31,158      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID64            16         28,242,452      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID72            16         22,906,973      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID80            16             72,898      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID88            16             56,907      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID96            16             20,456      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID104           16             40,913      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID112           16             78,113      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID120           16             37,897      ls_dmnd_fills_from_sys.ext_cache_remote

Also support 'perf stat record' and 'perf stat report' with the ability
to specify a different cache level to aggregate data at when running
'perf stat report'.

  $ sudo perf stat record --per-cache=L2 -a -e ls_dmnd_fills_from_sys.ext_cache_remote -- \
    taskset -c 0-15,64-79,128-143,192-207 \
    perf bench sched messaging -p -t -l 100000 -g 8

  ...

   Performance counter stats for 'system wide':

  S0-D0-L2-ID0              2          1,442,061      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L2-ID1              2          1,548,994      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L2-ID2              2          1,553,557      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L2-ID3              2          1,420,122      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L2-ID4              2          1,465,461      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L2-ID5              2          1,455,153      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L2-ID6              2          1,595,237      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L2-ID7              2          1,499,321      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L2-ID8              2          1,919,025      ls_dmnd_fills_from_sys.ext_cache_remote
  ...
  S1-D1-L2-ID127            2             21,295      ls_dmnd_fills_from_sys.ext_cache_remote

  $ sudo perf stat report --per-cache=L3

   Performance counter stats for 'perf stat record --per-cache=L2 -a -e ls_dmnd_fills_from_sys.ext_cache_remote --\
                                  taskset -c 0-15,64-79,128-143,192-207 \
                                  perf bench sched messaging -p -t -l 100000 -g 8':

  S0-D0-L3-ID0             16         11,979,906      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID8             16         14,257,202      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID16            16            377,484      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID24            16             27,224      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID32            16             26,816      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID40            16             14,461      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID48            16             10,499      ls_dmnd_fills_from_sys.ext_cache_remote
  S0-D0-L3-ID56            16             53,817      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID64            16         27,361,987      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID72            16         37,299,024      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID80            16             84,125      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID88            16             64,561      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID96            16             13,403      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID104           16             20,138      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID112           16             93,220      ls_dmnd_fills_from_sys.ext_cache_remote
  S1-D1-L3-ID120           16             35,465      ls_dmnd_fills_from_sys.ext_cache_remote

On the above system, the domain covered by S0-D0-L3-ID0 contains
S0-D0-L2-ID0 to S0-D0-L2-ID7, the corresponding count for L3-ID0 is
equal to the sum of counts for L2-ID0 to L2-ID7.

Add documentation for the newly introduced "--per-cache" option.
Suggested-by: Gautham Shenoy <gautham.shenoy@amd.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ananth Narayan <ananth.narayan@amd.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wen Pu <puwen@hygon.cn>
Link: https://lore.kernel.org/r/20230517172745.5833-5-kprateek.nayak@amd.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>