From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
Add a sample program that reads the trace buffer with the mapped open.
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
samples/Makefile | 2 ++
samples/cpu-map.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 92 insertions(+)
create mode 100644 samples/cpu-map.c
diff --git a/samples/Makefile b/samples/Makefile
index 81c8006f823e..7b68ae7ad34c 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -67,6 +67,8 @@ $(EXAMPLES): $(patsubst %,$(sdir)/%,$(TARGETS))
#
# $(bdir)/XX.o: $(bdir)/XX.c
# $(CC) -g -Wall $(CFLAGS) -c -o $@ $^ -I../include/ $(LIBTRACEEVENT_INCLUDES)
+$(bdir)/cpu-map.o: $(bdir)/cpu-map.c
+ $(CC) -g -Wall $(CFLAGS) -c -o $@ $^ -I../include/ $(LIBTRACEEVENT_INCLUDES)
$(bdir)/kprobes.o: $(bdir)/kprobes.c
$(CC) -g -Wall $(CFLAGS) -c -o $@ $^ -I../include/ $(LIBTRACEEVENT_INCLUDES)
diff --git a/samples/cpu-map.c b/samples/cpu-map.c
new file mode 100644
index 000000000000..b42742d8d073
--- /dev/null
+++ b/samples/cpu-map.c
@@ -0,0 +1,90 @@
+#include <stdlib.h>
+#include <ctype.h>
+#include <tracefs.h>
+
+static void read_subbuf(struct tep_handle *tep, struct kbuffer *kbuf)
+{
+ static struct trace_seq seq;
+ struct tep_record record;
+ int missed_events;
+
+ if (seq.buffer)
+ trace_seq_reset(&seq);
+ else
+ trace_seq_init(&seq);
+
+ while ((record.data = kbuffer_read_event(kbuf, &record.ts))) {
+ record.size = kbuffer_event_size(kbuf);
+ missed_events = kbuffer_missed_events(kbuf);
+ if (missed_events) {
+ printf("[MISSED EVENTS");
+ if (missed_events > 0)
+ printf(": %d]\n", missed_events);
+ else
+ printf("]\n");
+ }
+ kbuffer_next_event(kbuf, NULL);
+ tep_print_event(tep, &seq, &record,
+ "%s-%d %6.1000d\t%s: %s\n",
+ TEP_PRINT_COMM,
+ TEP_PRINT_PID,
+ TEP_PRINT_TIME,
+ TEP_PRINT_NAME,
+ TEP_PRINT_INFO);
+ trace_seq_do_printf(&seq);
+ trace_seq_reset(&seq);
+ }
+}
+
+int main (int argc, char **argv)
+{
+ struct tracefs_cpu *tcpu;
+ struct tep_handle *tep;
+ struct kbuffer *kbuf;
+ bool mapped;
+ int cpu;
+
+ if (argc < 2 || !isdigit(argv[1][0])) {
+ printf("usage: %s cpu\n\n", argv[0]);
+ exit(-1);
+ }
+
+ cpu = atoi(argv[1]);
+
+ tep = tracefs_local_events(NULL);
+ if (!tep) {
+ perror("Reading trace event formats");
+ exit(-1);
+ }
+
+ tcpu = tracefs_cpu_open_mapped(NULL, cpu, 0);
+ if (!tcpu) {
+ perror("Open CPU 0 file");
+ exit(-1);
+ }
+
+ /*
+ * If this kernel supports mapping, use normal read,
+ * otherwise use the piped buffer read, although if
+ * the mapping succeeded, tracefs_cpu_buffered_read_buf()
+ * acts the same as tracefs_cpu_read_buf(). But this is just
+ * an example on how to use tracefs_cpu_is_mapped().
+ */
+ mapped = tracefs_cpu_is_mapped(tcpu);
+ if (!mapped)
+ printf("Was not able to map, falling back to buffered read\n");
+ while ((kbuf = mapped ? tracefs_cpu_read_buf(tcpu, true) :
+ tracefs_cpu_buffered_read_buf(tcpu, true))) {
+ read_subbuf(tep, kbuf);
+ }
+
+ kbuf = tracefs_cpu_flush_buf(tcpu);
+ if (kbuf)
+ read_subbuf(tep, kbuf);
+
+ tracefs_cpu_close(tcpu);
+ tep_free(tep);
+
+ return 0;
+}
+
--
2.43.0
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