tracing: Add hist trigger support for compound keys

Allow users to specify multiple trace event fields to use in keys by
allowing multiple fields in the 'keys=' keyword.  With this addition,
any unique combination of any of the fields named in the 'keys'
keyword will result in a new entry being added to the hash table.

Link: http://lkml.kernel.org/r/0cfa24e6ac3b0dcece7737d94aa1f322ae3afc4b.1457029949.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index bb62f54c5480b5b2b34154c3af7cbd50ae5639e8..7a4c4dcf0bfeadb27e641e774125323cb19c194e 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3833,7 +3833,7 @@ static const char readme_msg[] =
        "\t   Filters can be ignored when removing a trigger.\n"
 #ifdef CONFIG_HIST_TRIGGERS
        "      hist trigger\t- If set, event hits are aggregated into a hash table\n"
-       "\t    Format: hist:keys=<field1>\n"
+       "\t    Format: hist:keys=<field1[,field2,...]>\n"
        "\t            [:values=<field1[,field2,...]>]\n"
        "\t            [:size=#entries]\n"
        "\t            [if <filter>]\n\n"
@@ -3841,9 +3841,11 @@ static const char readme_msg[] =
        "\t    table using the key(s) and value(s) named, and the value of a\n"
        "\t    sum called 'hitcount' is incremented.  Keys and values\n"
        "\t    correspond to fields in the event's format description.  Keys\n"
-       "\t    can be any field.  Values must correspond to numeric fields.\n"
-       "\t    The 'size' parameter can be  used to specify more or fewer\n"
-       "\t    than the default 2048 entries for the hashtable size.\n\n"
+       "\t    can be any field.  Compound keys consisting of up to two\n"
+       "\t    fields can be specified by the 'keys' keyword.  Values must\n"
+       "\t    correspond to numeric fields.  The 'size' parameter can be\n"
+       "\t    used to specify more or fewer than the default 2048 entries\n"
+       "\t    for the hashtable size.\n\n"
        "\t    Reading the 'hist' file for the event will dump the hash\n"
        "\t    table in its entirety to stdout."
 #endif

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1b33590b9c8fb512f8423d7d6538b460dccc4857..65fdfc6cb633d751bff00e40d33dcd4ff6d97099 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -32,6 +32,7 @@ struct hist_field {
        unsigned long                   flags;
        hist_field_fn_t                 fn;
        unsigned int                    size;
+       unsigned int                    offset;
 };
 
 static u64 hist_field_counter(struct hist_field *field, void *event)
@@ -73,8 +74,7 @@ DEFINE_HIST_FIELD_FN(u8);
        for ((i) = (hist_data)->n_vals; (i) < (hist_data)->n_fields; (i)++)
 
 #define HITCOUNT_IDX           0
-#define HIST_KEY_MAX           1
-#define HIST_KEY_SIZE_MAX      MAX_FILTER_STR_VAL
+#define HIST_KEY_SIZE_MAX      (MAX_FILTER_STR_VAL + sizeof(u64))
 
 enum hist_field_flags {
        HIST_FIELD_FL_HITCOUNT  = 1,
@@ -351,6 +351,7 @@ static int create_val_fields(struct hist_trigger_data *hist_data,
 
 static int create_key_field(struct hist_trigger_data *hist_data,
                            unsigned int key_idx,
+                           unsigned int key_offset,
                            struct trace_event_file *file,
                            char *field_str)
 {
@@ -380,7 +381,8 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 
        key_size = ALIGN(key_size, sizeof(u64));
        hist_data->fields[key_idx]->size = key_size;
-       hist_data->key_size = key_size;
+       hist_data->fields[key_idx]->offset = key_offset;
+       hist_data->key_size += key_size;
        if (hist_data->key_size > HIST_KEY_SIZE_MAX) {
                ret = -EINVAL;
                goto out;
@@ -399,7 +401,7 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 static int create_key_fields(struct hist_trigger_data *hist_data,
                             struct trace_event_file *file)
 {
-       unsigned int i, n_vals = hist_data->n_vals;
+       unsigned int i, key_offset = 0, n_vals = hist_data->n_vals;
        char *fields_str, *field_str;
        int ret = -EINVAL;
 
@@ -411,13 +413,15 @@ static int create_key_fields(struct hist_trigger_data *hist_data,
        if (!fields_str)
                goto out;
 
-       for (i = n_vals; i < n_vals + HIST_KEY_MAX; i++) {
+       for (i = n_vals; i < n_vals + TRACING_MAP_KEYS_MAX; i++) {
                field_str = strsep(&fields_str, ",");
                if (!field_str)
                        break;
-               ret = create_key_field(hist_data, i, file, field_str);
+               ret = create_key_field(hist_data, i, key_offset,
+                                      file, field_str);
                if (ret < 0)
                        goto out;
+               key_offset += ret;
        }
        if (fields_str) {
                ret = -EINVAL;
@@ -482,7 +486,10 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
                        else
                                cmp_fn = tracing_map_cmp_num(field->size,
                                                             field->is_signed);
-                       idx = tracing_map_add_key_field(map, 0, cmp_fn);
+                       idx = tracing_map_add_key_field(map,
+                                                       hist_field->offset,
+                                                       cmp_fn);
+
                } else
                        idx = tracing_map_add_sum_field(map);
 
@@ -562,12 +569,16 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
 static void event_hist_trigger(struct event_trigger_data *data, void *rec)
 {
        struct hist_trigger_data *hist_data = data->private_data;
+       char compound_key[HIST_KEY_SIZE_MAX];
        struct hist_field *key_field;
        struct tracing_map_elt *elt;
        u64 field_contents;
        void *key = NULL;
        unsigned int i;
 
+       if (hist_data->n_keys > 1)
+               memset(compound_key, 0, hist_data->key_size);
+
        for_each_hist_key_field(i, hist_data) {
                key_field = hist_data->fields[i];
 
@@ -576,8 +587,16 @@ static void event_hist_trigger(struct event_trigger_data *data, void *rec)
                        key = (void *)(unsigned long)field_contents;
                else
                        key = (void *)&field_contents;
+
+               if (hist_data->n_keys > 1) {
+                       memcpy(compound_key + key_field->offset, key,
+                              key_field->size);
+               }
        }
 
+       if (hist_data->n_keys > 1)
+               key = compound_key;
+
        elt = tracing_map_insert(hist_data->map, key);
        if (elt)
                hist_trigger_elt_update(hist_data, elt, rec);
@@ -602,11 +621,11 @@ hist_trigger_entry_print(struct seq_file *m,
 
                if (key_field->flags & HIST_FIELD_FL_STRING) {
                        seq_printf(m, "%s: %-50s", key_field->field->name,
-                                  (char *)key);
+                                  (char *)(key + key_field->offset));
                } else {
-                       uval = *(u64 *)key;
-                       seq_printf(m, "%s: %10llu",
-                                  key_field->field->name, uval);
+                       uval = *(u64 *)(key + key_field->offset);
+                       seq_printf(m, "%s: %10llu", key_field->field->name,
+                                  uval);
                }
        }