new file mode 100644
@@ -0,0 +1,183 @@
+libtracefs(3)
+=============
+
+NAME
+----
+tracefs_instance_get_stat, tracefs_instance_put_stat, tracefs_buffer_stat_entries, tracefs_buffer_stat_overrun,
+tracefs_buffer_stat_commit_overrun, tracefs_buffer_stat_bytes, tracefs_buffer_stat_event_timestamp,
+tracefs_buffer_stat_timestamp, tracefs_buffer_stat_dropped_events, tracefs_buffer_stat_read_events
+- Handling tracing buffer stats
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <tracefs.h>*
+
+struct tracefs_buffer_stat pass:[*]*tracefs_instance_get_stat*(struct tracefs_instance pass:[*]_instance_, int _cpu_);
+void *tracefs_instance_put_stat*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ssize_t *tracefs_buffer_stat_entries*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ssize_t *tracefs_buffer_stat_overrun*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ssize_t *tracefs_buffer_stat_commit_overrun*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ssize_t *tracefs_buffer_stat_bytes*(struct tracefs_buffer_stat pass:[*]_tstat_);
+long long *tracefs_buffer_stat_event_timestamp*(struct tracefs_buffer_stat pass:[*]_tstat_);
+long long *tracefs_buffer_stat_timestamp*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ssize_t *tracefs_buffer_stat_dropped_events*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ssize_t *tracefs_buffer_stat_read_events*(struct tracefs_buffer_stat pass:[*]_tstat_);
+--
+
+DESCRIPTION
+-----------
+This set of functions read and parse the tracefs/per_cpu/cpuX/stats file.
+These files hold the statistics of the per CPU ring buffer, such as how
+many events are in the ring buffer, how many have been read and so on.
+
+The *tracefs_instance_get_stat()* function will read and parse a given statistics
+file for a given _instance_ and _cpu_. As the ring buffer is split into per_cpu buffers,
+the information is only associated to the given _cpu_. The returned tracefs_buffer_stat
+pointer can be used with the other *tracefs_buffer_stat* functions and must be freed with
+*tracefs_instance_put_stat()*.
+
+The *tracefs_instance_put_stat()* will free the resources allocated for the given _stat_
+that was created by *tracefs_instance_get_stat()*.
+
+The *tracefs_buffer_stat_entries()* returns the number of events that are currently
+in the ring buffer associated with _tstat_.
+
+The *tracefs_buffer_stat_overrun()* returns the number of events that were lost by
+the ring buffer writer overrunning the reader.
+
+The *tracefs_buffer_stat_commit_overrun()* returns the number of events that were
+lost because the ring buffer was too small and an interrupt interrupted a lower
+context event being recorded and it added more events than the ring buffer could
+hold. Note this is not a common occurrence and when it happens it means that
+something was not set up properly.
+
+The *tracefs_buffer_stat_bytes()* returns the number of bytes that the current events
+take up. Note, it includes the meta data for the events, but does not include the
+meta data for the sub-buffers.
+
+The *tracefs_buffer_stat_event_timestamp()* returns the timestamp of the last event in the
+ring buffer.
+
+The *tracefs_buffer_stat_timestamp()* returns the current timestamp of the ring buffer.
+Note, it is only read when *tracefs_instance_get_stat()* is called. It will have the
+timestamp of the ring buffer when that function was called.
+
+The *tracefs_buffer_stat_dropped_events()* returns the number of events that were
+dropped if overwrite mode is disabled. It will show the events that were lost because
+the writer caught up to the reader and could not write any more events.
+
+The *tracefs_buffer_stat_read_events()* returns the number of events that were consumed
+by a reader.
+
+
+RETURN VALUE
+------------
+The *tracefs_instance_get_stat()* returns a tracefs_buffer_stat structure that can
+be used to retrieve the statistics via the other functions. It must be freed with
+*tracefs_instance_put_stat()*.
+
+The other functions that return different values from the tracefs_buffer_stat structure
+all return the value, or -1 if the value was not found.
+
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <stdlib.h>
+#include <unistd.h>
+#include <tracefs.h>
+
+int main(int argc, char **argv)
+{
+ char *trace;
+ char buf[1000];
+ int ret;
+ int i;
+
+ for (i = 0; i < sizeof(buf) - 1; i++) {
+ buf[i] = '0' + i % 10;
+ }
+ buf[i] = '\0';
+
+ tracefs_instance_clear(NULL);
+
+ for (i = 0; i < 4; i++) {
+ ret = tracefs_printf(NULL, "%s\n", buf);
+ if (ret < 0)
+ perror("write");
+ }
+
+ trace = tracefs_instance_file_read(NULL, "trace", NULL);
+ printf("%s\n", trace);
+ free(trace);
+
+ for (i = 0; i < sysconf(_SC_NPROCESSORS_CONF); i++) {
+ struct tracefs_buffer_stat *tstat;
+ ssize_t entries, eread;
+
+ tstat = tracefs_instance_get_stat(NULL, i);
+ if (!tstat)
+ continue;
+
+ entries = tracefs_buffer_stat_entries(tstat);
+ eread = tracefs_buffer_stat_read_events(tstat);
+ if (!entries && !eread) {
+ tracefs_instance_put_stat(tstat);
+ continue;
+ }
+
+ printf("CPU: %d\n", i);;
+ printf("\tentries: %zd\n", entries);
+ printf("\toverrun: %zd\n", tracefs_buffer_stat_overrun(tstat));
+ printf("\tcommit_overrun: %zd\n", tracefs_buffer_stat_commit_overrun(tstat));
+ printf("\tbytes: %zd\n", tracefs_buffer_stat_bytes(tstat));
+ printf("\tevent_timestamp: %lld\n", tracefs_buffer_stat_event_timestamp(tstat));
+ printf("\ttimestamp: %lld\n", tracefs_buffer_stat_timestamp(tstat));
+ printf("\tdropped_events: %zd\n", tracefs_buffer_stat_dropped_events(tstat));
+ printf("\tread_events: %zd\n", eread);
+
+ tracefs_instance_put_stat(tstat);
+ }
+}
+--
+FILES
+-----
+[verse]
+--
+*tracefs.h*
+ Header file to include in order to have access to the library APIs.
+*-ltracefs*
+ Linker switch to add when building a program that uses the library.
+--
+
+SEE ALSO
+--------
+*libtracefs*(3),
+*libtraceevent*(3),
+*trace-cmd*(1)
+
+AUTHOR
+------
+[verse]
+--
+*Steven Rostedt* <rostedt@goodmis.org>
+--
+REPORTING BUGS
+--------------
+Report bugs to <linux-trace-devel@vger.kernel.org>
+
+LICENSE
+-------
+libtracefs is Free Software licensed under the GNU LGPL 2.1
+
+RESOURCES
+---------
+https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
+
+COPYING
+-------
+Copyright \(C) 2020 VMware, Inc. Free use of this software is granted under
+the terms of the GNU Public License (GPL).
@@ -155,6 +155,18 @@ Writing data in the trace buffer:
Control library logs:
int *tracefs_set_loglevel*(enum tep_loglevel _level_);
+Read the ring buffer statistics:
+ struct tracefs_buffer_stat pass:[*]*tracefs_instance_get_stat*(struct tracefs_instance pass:[*]_instance_, int _cpu_);
+ void *tracefs_instance_put_stat*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ ssize_t *tracefs_buffer_stat_entries*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ ssize_t *tracefs_buffer_stat_overrun*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ ssize_t *tracefs_buffer_stat_commit_overrun*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ ssize_t *tracefs_buffer_stat_bytes*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ long long *tracefs_buffer_stat_event_timestamp*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ long long *tracefs_buffer_stat_timestamp*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ ssize_t *tracefs_buffer_stat_dropped_events*(struct tracefs_buffer_stat pass:[*]_tstat_);
+ ssize_t *tracefs_buffer_stat_read_events*(struct tracefs_buffer_stat pass:[*]_tstat_);
+
Dynamic event generic APIs:
struct *tracefs_dynevent*;
enum *tracefs_dynevent_type*;
@@ -51,6 +51,17 @@ struct tracefs_instance {
bool iterate_keep_going;
};
+struct tracefs_buffer_stat {
+ ssize_t entries;
+ ssize_t overrun;
+ ssize_t commit_overrun;
+ ssize_t bytes;
+ long long oldest_ts;
+ long long now_ts;
+ ssize_t dropped_events;
+ ssize_t read_events;
+};
+
extern const struct tep_format_field common_stacktrace;
extern pthread_mutex_t toplevel_lock;
@@ -68,6 +68,19 @@ char **tracefs_instances(const char *regex);
int tracefs_instance_get_buffer_percent(struct tracefs_instance *instance);
int tracefs_instance_set_buffer_percent(struct tracefs_instance *instance, int val);
+struct tracefs_buffer_stat;
+
+struct tracefs_buffer_stat *tracefs_instance_get_stat(struct tracefs_instance *instance, int cpu);
+void tracefs_instance_put_stat(struct tracefs_buffer_stat *tstat);
+ssize_t tracefs_buffer_stat_entries(struct tracefs_buffer_stat *tstat);
+ssize_t tracefs_buffer_stat_overrun(struct tracefs_buffer_stat *tstat);
+ssize_t tracefs_buffer_stat_commit_overrun(struct tracefs_buffer_stat *tstat);
+ssize_t tracefs_buffer_stat_bytes(struct tracefs_buffer_stat *tstat);
+long long tracefs_buffer_stat_event_timestamp(struct tracefs_buffer_stat *tstat);
+long long tracefs_buffer_stat_timestamp(struct tracefs_buffer_stat *tstat);
+ssize_t tracefs_buffer_stat_dropped_events(struct tracefs_buffer_stat *tstat);
+ssize_t tracefs_buffer_stat_read_events(struct tracefs_buffer_stat *tstat);
+
bool tracefs_instance_exists(const char *name);
bool tracefs_file_exists(struct tracefs_instance *instance, const char *name);
bool tracefs_dir_exists(struct tracefs_instance *instance, const char *name);
@@ -24,6 +24,7 @@ EXAMPLES += instances-affinity
EXAMPLES += cpu
EXAMPLES += guest
EXAMPLES += cpu-buf
+EXAMPLES += instances-stat
TARGETS :=
TARGETS += sqlhist
@@ -10,6 +10,7 @@ OBJS += tracefs-tools.o
OBJS += tracefs-marker.o
OBJS += tracefs-kprobes.o
OBJS += tracefs-hist.o
+OBJS += tracefs-stats.o
OBJS += tracefs-filter.o
OBJS += tracefs-dynevents.o
OBJS += tracefs-eprobes.o
new file mode 100644
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * Copyright (C) 2023 Google LLC, Steven Rostedt <rostedt@goodmis.org>
+ */
+#include <stdlib.h>
+#include <ctype.h>
+#include "tracefs.h"
+#include "tracefs-local.h"
+
+static long long convert_ts(char *value)
+{
+ long long ts;
+ char *saveptr;
+ char *secs;
+ char *usecs;
+
+ secs = strtok_r(value, ".", &saveptr);
+ if (!secs)
+ return -1LL;
+
+ ts = strtoll(secs, NULL, 0);
+
+ usecs = strtok_r(NULL, ".", &saveptr);
+ if (!usecs)
+ return ts;
+
+ /* Could be in nanoseconds */
+ if (strlen(usecs) > 6)
+ ts *= 1000000000LL;
+ else
+ ts *= 1000000LL;
+
+ ts += strtoull(usecs, NULL, 0);
+
+ return ts;
+}
+
+struct tracefs_buffer_stat *
+tracefs_instance_get_stat(struct tracefs_instance *instance, int cpu)
+{
+ struct tracefs_buffer_stat *tstat;
+ char *saveptr;
+ char *value;
+ char *field;
+ char *path;
+ char *line;
+ char *next;
+ char *buf;
+ int len;
+ int ret;
+
+ ret = asprintf(&path, "per_cpu/cpu%d/stats", cpu);
+ if (ret < 0)
+ return NULL;
+
+ buf = tracefs_instance_file_read(instance, path, &len);
+ free(path);
+
+ if (!buf)
+ return NULL;
+
+ tstat = malloc(sizeof(*tstat));
+ if (!tstat) {
+ free(buf);
+ return NULL;
+ }
+
+ /* Set everything to -1 */
+ memset(tstat, -1, sizeof(*tstat));
+
+ next = buf;
+ while ((line = strtok_r(next, "\n", &saveptr))) {
+ char *save2;
+
+ next = NULL;
+
+ field = strtok_r(line, ":", &save2);
+ if (!field)
+ break;
+
+ value = strtok_r(NULL, ":", &save2);
+ if (!value)
+ break;
+
+ while (isspace(*value))
+ value++;
+
+ if (strcmp(field, "entries") == 0) {
+ tstat->entries = strtoull(value, NULL, 0);
+
+ } else if (strcmp(field, "overrun") == 0) {
+ tstat->overrun = strtoull(value, NULL, 0);
+
+ } else if (strcmp(field, "commit overrun") == 0) {
+ tstat->commit_overrun = strtoull(value, NULL, 0);
+
+ } else if (strcmp(field, "bytes") == 0) {
+ tstat->bytes = strtoull(value, NULL, 0);
+
+ } else if (strcmp(field, "oldest event ts") == 0) {
+ tstat->oldest_ts = convert_ts(value);
+
+ } else if (strcmp(field, "now ts") == 0) {
+ tstat->now_ts = convert_ts(value);
+
+ } else if (strcmp(field, "dropped events") == 0) {
+ tstat->dropped_events = strtoull(value, NULL, 0);
+
+ } else if (strcmp(field, "read events") == 0) {
+ tstat->read_events = strtoull(value, NULL, 0);
+ }
+ }
+ free(buf);
+
+ return tstat;
+}
+
+void tracefs_instance_put_stat(struct tracefs_buffer_stat *tstat)
+{
+ free(tstat);
+}
+
+ssize_t tracefs_buffer_stat_entries(struct tracefs_buffer_stat *tstat)
+{
+ return tstat->entries;
+}
+
+ssize_t tracefs_buffer_stat_overrun(struct tracefs_buffer_stat *tstat)
+{
+ return tstat->overrun;
+}
+
+ssize_t tracefs_buffer_stat_commit_overrun(struct tracefs_buffer_stat *tstat)
+{
+ return tstat->commit_overrun;
+}
+
+ssize_t tracefs_buffer_stat_bytes(struct tracefs_buffer_stat *tstat)
+{
+ return tstat->bytes;
+}
+
+long long tracefs_buffer_stat_event_timestamp(struct tracefs_buffer_stat *tstat)
+{
+ return tstat->oldest_ts;
+}
+
+long long tracefs_buffer_stat_timestamp(struct tracefs_buffer_stat *tstat)
+{
+ return tstat->now_ts;
+}
+
+ssize_t tracefs_buffer_stat_dropped_events(struct tracefs_buffer_stat *tstat)
+{
+ return tstat->dropped_events;
+}
+
+ssize_t tracefs_buffer_stat_read_events(struct tracefs_buffer_stat *tstat)
+{
+ return tstat->read_events;
+}
+