Enable perf PMU counters by raw ID
authorJulien Desfossez <jdesfossez@efficios.com>
Tue, 5 Jul 2016 15:50:46 +0000 (11:50 -0400)
committerJérémie Galarneau <jeremie.galarneau@efficios.com>
Fri, 8 Jul 2016 19:23:56 +0000 (15:23 -0400)
Allow enabling perf PMU counters by raw ID in addition to the generic
list already provided. The format for kernel tracing is
"perf:cpu:raw:rNNN:<name>" and "perf:thread:raw:rNNN:<name> for
user-space. The rNNN format is the same as perf-record(1) where NNN is a
hexadecimal event descriptor in the form of umask+eventsel. The <name>
field to associate a clearer name to the counter.

Example usage on Intel i7-3520M to get the unhalted reference cycles
(eventsel: 0x13c) count at privilege level 0 (umask: 0x00):
lttng add-context -k -t perf:cpu:raw:r0013c:x86unhalted

Result in the trace:
sched_switch: { cpu_id = 3 }, {
perf_cpu_raw_r0013c_x86unhalted = 27632578 }, [...]

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
doc/man/lttng-add-context.1.txt
src/bin/lttng/commands/add_context.c

index f995a7fbe2fd629f1091c68427edc30fc3410db8..a1e0fe78f14035015e00c7bd4185b9f3f7a2b732 100644 (file)
@@ -45,6 +45,15 @@ per-thread (`perf:thread:` prefix) counters. Currently, per-CPU counters
 can only be used in the Linux kernel tracing domain, while per-thread
 counters can only be used in the user space tracing domain.
 
+It is also possible to enable PMU counters by raw ID using the
+`perf:cpu:raw:r<N>:<name>` or `perf:thread:raw:r<N>:<name>` format for
+the kernel and user-space respectively. `<N>` is a hexadecimal event
+descriptor which is the same format as used by perf-record(1): a
+concatenation of the `Umask value` and `Event number` provided by the
+processor's manufacturer. The possible values for this field are
+processor-specific. The `<name>` field is used to associate a clearer
+name to the counter.
+
 Application-specific context fields can be added to a channel using the
 following syntax:
 
index 2f43dc7ff203e53a411d7178e649d80dd590d824..5fc65bf556e7db963659e74dcbf0c90e27b44264 100644 (file)
@@ -87,6 +87,7 @@ enum perf_type {
        PERF_TYPE_HARDWARE = 0,
        PERF_TYPE_SOFTWARE = 1,
        PERF_TYPE_HW_CACHE = 3,
+       PERF_TYPE_RAW = 4,
 };
 
 enum perf_count_hard {
@@ -687,10 +688,101 @@ end:
        return type;
 }
 
+static
+int find_ctx_type_perf_raw(const char *ctx, struct ctx_type *type)
+{
+       int ret;
+       int field_pos = 0;
+       char *tmp_list, *cur_list;
+
+       cur_list = tmp_list = strdup(ctx);
+       if (!tmp_list) {
+               PERROR("strdup temp list");
+               ret = -ENOMEM;
+               goto end;
+       }
+
+       /* Looking for "perf:[cpu|thread]:raw:<mask>:<name>". */
+       for (;;) {
+               char *next;
+
+               next = strtok(cur_list, ":");
+               if (!next) {
+                       break;
+               }
+               cur_list = NULL;
+               switch (field_pos) {
+               case 0:
+                       if (strncmp(next, "perf", 4) != 0) {
+                               ret = -1;
+                               goto end;
+                       }
+                       break;
+               case 1:
+                       if (strncmp(next, "cpu", 3) == 0) {
+                               type->opt->ctx_type = CONTEXT_PERF_CPU_COUNTER;
+                       } else if (strncmp(next, "thread", 4) == 0) {
+                               type->opt->ctx_type = CONTEXT_PERF_THREAD_COUNTER;
+                       } else {
+                               ret = -1;
+                               goto end;
+                       }
+                       break;
+               case 2:
+                       if (strncmp(next, "raw", 3) != 0) {
+                               ret = -1;
+                               goto end;
+                       }
+                       break;
+               case 3:
+               {
+                       char *endptr;
+
+                       if (strlen(next) < 2 || next[0] != 'r') {
+                               ERR("Wrong perf raw mask format: expected rNNN");
+                               ret = -1;
+                               goto end;
+                       }
+                       errno = 0;
+                       type->opt->u.perf.config = strtoll(next +  1, &endptr, 16);
+                       if (errno != 0 || !endptr || *endptr) {
+                               ERR("Wrong perf raw mask format: expected rNNN");
+                               ret = -1;
+                               goto end;
+                       }
+                       break;
+               }
+               case 4:
+                       /* name */
+                       break;
+               case 5:
+                       ERR("Too many ':' in perf raw format");
+                       ret = -1;
+                       goto end;
+               };
+               field_pos++;
+       }
+
+       if (field_pos < 5) {
+               ERR("Invalid perf counter specifier, expected a specifier of "
+                       "the form perf:cpu:raw:rNNN:<name> or "
+                       "perf:thread:raw:rNNN:<name>");
+               ret = -1;
+               goto end;
+       }
+
+       ret = 0;
+       goto end;
+
+end:
+       free(tmp_list);
+       return ret;
+}
+
 static
 struct ctx_type *get_context_type(const char *ctx)
 {
-       int opt_index;
+       int opt_index, ret;
        struct ctx_type *type = NULL;
        const char app_ctx_prefix[] = "$app.";
        char *provider_name = NULL, *ctx_name = NULL;
@@ -713,6 +805,18 @@ struct ctx_type *get_context_type(const char *ctx)
                goto found;
        }
 
+       /* Check if ctx is a raw perf context. */
+       ret = find_ctx_type_perf_raw(ctx, type);
+       if (ret == 0) {
+               type->opt->u.perf.type = PERF_TYPE_RAW;
+               type->opt->symbol = strdup(ctx);
+               if (!type->opt->symbol) {
+                       PERROR("Copy perf field name");
+                       goto not_found;
+               }
+               goto found;
+       }
+
        /*
         * No match found against static contexts; check if it is an app
         * context.
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