perf header: Add HEADER_GROUP_DESC feature

Save group relationship information so that it can be restored when perf
report is running.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1358845787-1350-4-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

3 files changed, 169 insertions, 0 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 2ac690cad411..774c90713a53 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -486,6 +486,9 @@ static int __cmd_record(struct perf_record *rec, int argc, const char **argv)
                 goto out_delete_session;
         }
 
+        if (!evsel_list->nr_groups)
+                perf_header__clear_feat(&session->header, HEADER_GROUP_DESC);
+
         /*
          * perf_session__delete(session) will be called at perf_record__exit()
          */
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index f6081cb3fca3..8022b5254f75 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1085,6 +1085,52 @@ static int write_pmu_mappings(int fd, struct perf_header *h __maybe_unused,
 }
 
 /*
+ * File format:
+ *
+ * struct group_descs {
+ *      u32     nr_groups;
+ *      struct group_desc {
+ *              char    name[];
+ *              u32     leader_idx;
+ *              u32     nr_members;
+ *      }[nr_groups];
+ * };
+ */
+static int write_group_desc(int fd, struct perf_header *h __maybe_unused,
+                            struct perf_evlist *evlist)
+{
+        u32 nr_groups = evlist->nr_groups;
+        struct perf_evsel *evsel;
+        int ret;
+
+        ret = do_write(fd, &nr_groups, sizeof(nr_groups));
+        if (ret < 0)
+                return ret;
+
+        list_for_each_entry(evsel, &evlist->entries, node) {
+                if (perf_evsel__is_group_leader(evsel) &&
+                    evsel->nr_members > 1) {
+                        const char *name = evsel->group_name ?: "{anon_group}";
+                        u32 leader_idx = evsel->idx;
+                        u32 nr_members = evsel->nr_members;
+
+                        ret = do_write_string(fd, name);
+                        if (ret < 0)
+                                return ret;
+
+                        ret = do_write(fd, &leader_idx, sizeof(leader_idx));
+                        if (ret < 0)
+                                return ret;
+
+                        ret = do_write(fd, &nr_members, sizeof(nr_members));
+                        if (ret < 0)
+                                return ret;
+                }
+        }
+        return 0;
+}
+
+/*
  * default get_cpuid(): nothing gets recorded
  * actual implementation must be in arch/$(ARCH)/util/header.c
  */
@@ -1447,6 +1493,31 @@ error:
         fprintf(fp, "# pmu mappings: unable to read\n");
 }
 
+static void print_group_desc(struct perf_header *ph, int fd __maybe_unused,
+                             FILE *fp)
+{
+        struct perf_session *session;
+        struct perf_evsel *evsel;
+        u32 nr = 0;
+
+        session = container_of(ph, struct perf_session, header);
+
+        list_for_each_entry(evsel, &session->evlist->entries, node) {
+                if (perf_evsel__is_group_leader(evsel) &&
+                    evsel->nr_members > 1) {
+                        fprintf(fp, "# group: %s{%s", evsel->group_name ?: "",
+                                perf_evsel__name(evsel));
+
+                        nr = evsel->nr_members - 1;
+                } else if (nr) {
+                        fprintf(fp, ",%s", perf_evsel__name(evsel));
+
+                        if (--nr == 0)
+                                fprintf(fp, "}\n");
+                }
+        }
+}
+
 static int __event_process_build_id(struct build_id_event *bev,
                                     char *filename,
                                     struct perf_session *session)
@@ -1961,6 +2032,98 @@ error:
         return -1;
 }
 
+static int process_group_desc(struct perf_file_section *section __maybe_unused,
+                              struct perf_header *ph, int fd,
+                              void *data __maybe_unused)
+{
+        size_t ret = -1;
+        u32 i, nr, nr_groups;
+        struct perf_session *session;
+        struct perf_evsel *evsel, *leader = NULL;
+        struct group_desc {
+                char *name;
+                u32 leader_idx;
+                u32 nr_members;
+        } *desc;
+
+        if (readn(fd, &nr_groups, sizeof(nr_groups)) != sizeof(nr_groups))
+                return -1;
+
+        if (ph->needs_swap)
+                nr_groups = bswap_32(nr_groups);
+
+        ph->env.nr_groups = nr_groups;
+        if (!nr_groups) {
+                pr_debug("group desc not available\n");
+                return 0;
+        }
+
+        desc = calloc(nr_groups, sizeof(*desc));
+        if (!desc)
+                return -1;
+
+        for (i = 0; i < nr_groups; i++) {
+                desc[i].name = do_read_string(fd, ph);
+                if (!desc[i].name)
+                        goto out_free;
+
+                if (readn(fd, &desc[i].leader_idx, sizeof(u32)) != sizeof(u32))
+                        goto out_free;
+
+                if (readn(fd, &desc[i].nr_members, sizeof(u32)) != sizeof(u32))
+                        goto out_free;
+
+                if (ph->needs_swap) {
+                        desc[i].leader_idx = bswap_32(desc[i].leader_idx);
+                        desc[i].nr_members = bswap_32(desc[i].nr_members);
+                }
+        }
+
+        /*
+         * Rebuild group relationship based on the group_desc
+         */
+        session = container_of(ph, struct perf_session, header);
+        session->evlist->nr_groups = nr_groups;
+
+        i = nr = 0;
+        list_for_each_entry(evsel, &session->evlist->entries, node) {
+                if (evsel->idx == (int) desc[i].leader_idx) {
+                        evsel->leader = evsel;
+                        /* {anon_group} is a dummy name */
+                        if (strcmp(desc[i].name, "{anon_group}"))
+                                evsel->group_name = desc[i].name;
+                        evsel->nr_members = desc[i].nr_members;
+
+                        if (i >= nr_groups || nr > 0) {
+                                pr_debug("invalid group desc\n");
+                                goto out_free;
+                        }
+
+                        leader = evsel;
+                        nr = evsel->nr_members - 1;
+                        i++;
+                } else if (nr) {
+                        /* This is a group member */
+                        evsel->leader = leader;
+
+                        nr--;
+                }
+        }
+
+        if (i != nr_groups || nr != 0) {
+                pr_debug("invalid group desc\n");
+                goto out_free;
+        }
+
+        ret = 0;
+out_free:
+        while ((int) --i >= 0)
+                free(desc[i].name);
+        free(desc);
+
+        return ret;
+}
+
 struct feature_ops {
         int (*write)(int fd, struct perf_header *h, struct perf_evlist *evlist);
         void (*print)(struct perf_header *h, int fd, FILE *fp);
@@ -2000,6 +2163,7 @@ static const struct feature_ops feat_ops[HEADER_LAST_FEATURE] = {
         FEAT_OPF(HEADER_NUMA_TOPOLOGY,  numa_topology),
         FEAT_OPA(HEADER_BRANCH_STACK,   branch_stack),
         FEAT_OPP(HEADER_PMU_MAPPINGS,   pmu_mappings),
+        FEAT_OPP(HEADER_GROUP_DESC,     group_desc),
 };
 
 struct header_print_data {
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index 20f0344accb1..c9fc55cada6d 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -29,6 +29,7 @@ enum {
         HEADER_NUMA_TOPOLOGY,
         HEADER_BRANCH_STACK,
         HEADER_PMU_MAPPINGS,
+        HEADER_GROUP_DESC,
         HEADER_LAST_FEATURE,
         HEADER_FEAT_BITS        = 256,
 };
@@ -79,6 +80,7 @@ struct perf_session_env {
         char                    *numa_nodes;
         int                     nr_pmu_mappings;
         char                    *pmu_mappings;
+        int                     nr_groups;
 };
 
 struct perf_header {