perf tools: Add 'S' event/group modifier to read sample value

Adding 'S' event/group modifier to specify that the event value/s are
read by PERF_SAMPLE_READ sample type processing, instead of the period
value offered by lower layers.

There's additional behaviour change for 'S' modifier being specified on
event group:

Currently all the events within a group makes samples. If user now
specifies 'S' within group modifier, only the leader will trigger
samples. The rest of events in the group will have sampling disabled.

And same as for single events, values of all events within the group
(including leader) are read by PERF_SAMPLE_READ sample type processing.

Following example will create event group with cycles and cache-misses
events, setting the cycles as group leader and the only event to
actually sample. Both cycles and cache-misses event period values are
read by PERF_SAMPLE_READ sample type processing with PERF_FORMAT_GROUP
read format.

Example:

  $ perf record -e '{cycles,cache-misses}:S' ls
  ...
  $ perf report --group --show-total-period --stdio
  ...
  # Samples: 36  of event 'anon group { cycles, cache-misses }'
  # Event count (approx.): 12585593
  #
  #       Overhead          Period  Command      Shared Object                      Symbol
  # ..............  ..............  .......  .................  ..........................
  #
    19.92%   1.20%  2505936     31       ls  [kernel.kallsyms]  [k] mark_held_locks
    13.74%   0.47%  1729327     12       ls  [kernel.kallsyms]  [k] sched_clock_local
    13.64%  23.72%  1716147    612       ls  ld-2.14.90.so      [.] check_match.10805
    13.12%  23.22%  1650778    599       ls  libc-2.14.90.so    [.] _nl_intern_locale_data
    11.24%  29.19%  1414554    753       ls  [kernel.kallsyms]  [k] sched_clock_cpu
     8.50%   0.35%  1070150      9       ls  [kernel.kallsyms]  [k] check_chain_key
  ...

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-iyoinu3axi11mymwnh2b7fxj@git.kernel.org
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 826f3d6d1d289ee34480ca977e097f7243e70719..eb03f063f0a2a0b71a7de5b84e25e26dfe2ff581 100644 (file)
--- a/tools/perf/Documentation/perf-list.txt
+++ b/tools/perf/Documentation/perf-list.txt
@@ -29,6 +29,7 @@ counted. The following modifiers exist:
  G - guest counting (in KVM guests)
  H - host counting (not in KVM guests)
  p - precise level
+ S - read sample value (PERF_SAMPLE_READ)
 
 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.c b/tools/perf/util/evsel.c
index 9ab8fff74e30c8b949d5c122a23296cf04040dac..8f1016186d57a62b80c75da9c8f7cb2cdd3d523c 100644 (file)
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -490,6 +490,7 @@ int perf_evsel__group_desc(struct perf_evsel *evsel, char *buf, size_t size)
 void perf_evsel__config(struct perf_evsel *evsel,
                        struct perf_record_opts *opts)
 {
+       struct perf_evsel *leader = evsel->leader;
        struct perf_event_attr *attr = &evsel->attr;
        int track = !evsel->idx; /* only the first counter needs these */
 
@@ -499,6 +500,25 @@ void perf_evsel__config(struct perf_evsel *evsel,
        perf_evsel__set_sample_bit(evsel, IP);
        perf_evsel__set_sample_bit(evsel, TID);
 
+       if (evsel->sample_read) {
+               perf_evsel__set_sample_bit(evsel, READ);
+
+               /*
+                * We need ID even in case of single event, because
+                * PERF_SAMPLE_READ process ID specific data.
+                */
+               perf_evsel__set_sample_id(evsel);
+
+               /*
+                * Apply group format only if we belong to group
+                * with more than one members.
+                */
+               if (leader->nr_members > 1) {
+                       attr->read_format |= PERF_FORMAT_GROUP;
+                       attr->inherit = 0;
+               }
+       }
+
        /*
         * We default some events to a 1 default interval. But keep
         * it a weak assumption overridable by the user.
@@ -514,6 +534,15 @@ void perf_evsel__config(struct perf_evsel *evsel,
                }
        }
 
+       /*
+        * Disable sampling for all group members other
+        * than leader in case leader 'leads' the sampling.
+        */
+       if ((leader != evsel) && leader->sample_read) {
+               attr->sample_freq   = 0;
+               attr->sample_period = 0;
+       }
+
        if (opts->no_samples)
                attr->sample_freq = 0;
 

diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 6a2cf261f38e4de02b6cf6973dac5ecd61cd9c85..5edc625b6ecdc4ac847756e32b12f0dfb5924173 100644 (file)
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -79,6 +79,7 @@ struct perf_evsel {
        /* parse modifier helper */
        int                     exclude_GH;
        int                     nr_members;
+       int                     sample_read;
        struct perf_evsel       *leader;
        char                    *group_name;
 };

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 2c460ede0a69de878b71d187ec74b59568117d92..dba877dc9482cd4c1974ec220d9de0234ec6601f 100644 (file)
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -687,6 +687,7 @@ struct event_modifier {
        int eG;
        int precise;
        int exclude_GH;
+       int sample_read;
 };
 
 static int get_event_modifier(struct event_modifier *mod, char *str,
@@ -698,6 +699,7 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
        int eH = evsel ? evsel->attr.exclude_host : 0;
        int eG = evsel ? evsel->attr.exclude_guest : 0;
        int precise = evsel ? evsel->attr.precise_ip : 0;
+       int sample_read = 0;
 
        int exclude = eu | ek | eh;
        int exclude_GH = evsel ? evsel->exclude_GH : 0;
@@ -730,6 +732,8 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
                        /* use of precise requires exclude_guest */
                        if (!exclude_GH)
                                eG = 1;
+               } else if (*str == 'S') {
+                       sample_read = 1;
                } else
                        break;
 
@@ -756,6 +760,7 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
        mod->eG = eG;
        mod->precise = precise;
        mod->exclude_GH = exclude_GH;
+       mod->sample_read = sample_read;
        return 0;
 }
 
@@ -768,7 +773,7 @@ static int check_modifier(char *str)
        char *p = str;
 
        /* The sizeof includes 0 byte as well. */
-       if (strlen(str) > (sizeof("ukhGHppp") - 1))
+       if (strlen(str) > (sizeof("ukhGHpppS") - 1))
                return -1;
 
        while (*p) {
@@ -806,6 +811,7 @@ int parse_events__modifier_event(struct list_head *list, char *str, bool add)
                evsel->attr.exclude_host   = mod.eH;
                evsel->attr.exclude_guest  = mod.eG;
                evsel->exclude_GH          = mod.exclude_GH;
+               evsel->sample_read         = mod.sample_read;
        }
 
        return 0;

diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
index e9d1134c2c68e97cdee78c889fd70156b5351497..b36115fe416aaaa7091f11952a48e006f57630ba 100644 (file)
--- a/tools/perf/util/parse-events.l
+++ b/tools/perf/util/parse-events.l
@@ -82,7 +82,7 @@ num_hex               0x[a-fA-F0-9]+
 num_raw_hex    [a-fA-F0-9]+
 name           [a-zA-Z_*?][a-zA-Z0-9_*?]*
 name_minus     [a-zA-Z_*?][a-zA-Z0-9\-_*?]*
-modifier_event [ukhpGH]+
+modifier_event [ukhpGHS]+
 modifier_bp    [rwx]{1,3}
 
 %%