Though extremely rare, there can be duplicate entries in the tracing map. This isn't normally a problem, as the sorting code makes this transparent by merging them during the sort.
It's useful to know however, as a check on that assumption - if a non-zero duplicate count is seen more than rarely, it might indicate an unexpected change to the algorithm, or a pathological data set. Add an extra param to tracing_map_sort_entries() and use it to display the value in the hist trigger output. Signed-off-by: Tom Zanussi <[email protected]> --- kernel/trace/trace_events_hist.c | 14 ++++++++------ kernel/trace/tracing_map.c | 12 +++++++++--- kernel/trace/tracing_map.h | 3 ++- 3 files changed, 19 insertions(+), 10 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 53a0634..ab94e2a 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -4011,7 +4011,8 @@ static void hist_trigger_stacktrace_print(struct seq_file *m, } static int print_entries(struct seq_file *m, - struct hist_trigger_data *hist_data) + struct hist_trigger_data *hist_data, + unsigned int *n_dups) { struct tracing_map_sort_entry **sort_entries = NULL; struct tracing_map *map = hist_data->map; @@ -4019,7 +4020,7 @@ static int print_entries(struct seq_file *m, n_entries = tracing_map_sort_entries(map, hist_data->sort_keys, hist_data->n_sort_keys, - &sort_entries); + &sort_entries, n_dups); if (n_entries < 0) return n_entries; @@ -4038,6 +4039,7 @@ static void hist_trigger_show(struct seq_file *m, { struct hist_trigger_data *hist_data; int n_entries, ret = 0; + unsigned int n_dups; if (n > 0) seq_puts(m, "\n\n"); @@ -4047,15 +4049,15 @@ static void hist_trigger_show(struct seq_file *m, seq_puts(m, "#\n\n"); hist_data = data->private_data; - n_entries = print_entries(m, hist_data); + n_entries = print_entries(m, hist_data, &n_dups); if (n_entries < 0) { ret = n_entries; n_entries = 0; } - seq_printf(m, "\nTotals:\n Hits: %llu\n Entries: %u\n Dropped: %llu\n", - (u64)atomic64_read(&hist_data->map->hits), - n_entries, (u64)atomic64_read(&hist_data->map->drops)); + seq_printf(m, "\nTotals:\n Hits: %llu\n Entries: %u\n Dropped: %llu\n Duplicates: %u\n", + (u64)atomic64_read(&hist_data->map->hits), n_entries, + (u64)atomic64_read(&hist_data->map->drops), n_dups); } static int hist_show(struct seq_file *m, void *v) diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c index f987069..9ed04b6 100644 --- a/kernel/trace/tracing_map.c +++ b/kernel/trace/tracing_map.c @@ -1084,6 +1084,7 @@ static void sort_secondary(struct tracing_map *map, * @map: The tracing_map * @sort_key: The sort key to use for sorting * @sort_entries: outval: pointer to allocated and sorted array of entries + * @n_dups: outval: pointer to variable receiving a count of duplicates found * * tracing_map_sort_entries() sorts the current set of entries in the * map and returns the list of tracing_map_sort_entries containing @@ -1100,13 +1101,16 @@ static void sort_secondary(struct tracing_map *map, * The client should not hold on to the returned array but should use * it and call tracing_map_destroy_sort_entries() when done. * - * Return: the number of sort_entries in the struct tracing_map_sort_entry - * array, negative on error + * Return: the number of sort_entries in the struct + * tracing_map_sort_entry array, negative on error. If n_dups is + * non-NULL, it will receive the number of duplicate entries found + * (and merged) during the sort. */ int tracing_map_sort_entries(struct tracing_map *map, struct tracing_map_sort_key *sort_keys, unsigned int n_sort_keys, - struct tracing_map_sort_entry ***sort_entries) + struct tracing_map_sort_entry ***sort_entries, + unsigned int *n_dups) { int (*cmp_entries_fn)(const struct tracing_map_sort_entry **, const struct tracing_map_sort_entry **); @@ -1147,6 +1151,8 @@ int tracing_map_sort_entries(struct tracing_map *map, if (ret < 0) goto free; n_entries -= ret; + if (n_dups) + *n_dups = ret; if (is_key(map, sort_keys[0].field_idx)) cmp_entries_fn = cmp_entries_key; diff --git a/kernel/trace/tracing_map.h b/kernel/trace/tracing_map.h index 303bc4f..a44cc0c 100644 --- a/kernel/trace/tracing_map.h +++ b/kernel/trace/tracing_map.h @@ -286,7 +286,8 @@ extern void tracing_map_set_field_descr(struct tracing_map *map, tracing_map_sort_entries(struct tracing_map *map, struct tracing_map_sort_key *sort_keys, unsigned int n_sort_keys, - struct tracing_map_sort_entry ***sort_entries); + struct tracing_map_sort_entry ***sort_entries, + unsigned int *n_dups); extern void tracing_map_destroy_sort_entries(struct tracing_map_sort_entry **entries, -- 1.9.3
