[3/4] libtracefs: Use mmapping for iterating raw events

Commit Message

Steven Rostedt Jan. 9, 2024, 8:48 p.m. UTC

From: "Steven Rostedt (Google)" <[e-mail]>

If mmapping the ring buffer is available, use that for iterating raw events
as it's less copying than using splice buffering.

Signed-off-by: Steven Rostedt (Google) <[e-mail]>
---
 src/tracefs-events.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Patch

diff --git a/src/tracefs-events.c b/src/tracefs-events.c
index 2571c4b43341..9f620abebdda 100644
--- a/src/tracefs-events.c
+++ b/src/tracefs-events.c
@@ -32,6 +32,7 @@  struct cpu_iterate {
 	struct tep_event *event;
 	struct kbuffer *kbuf;
 	int cpu;
+	bool mapped;
 };
 
 static int read_kbuf_record(struct cpu_iterate *cpu)
@@ -66,7 +67,11 @@  int read_next_page(struct tep_handle *tep, struct cpu_iterate *cpu)
 	if (!cpu->tcpu)
 		return -1;
 
-	kbuf = tracefs_cpu_buffered_read_buf(cpu->tcpu, true);
+	/* Do not do buffered reads if it is mapped */
+	if (cpu->mapped)
+		kbuf = tracefs_cpu_read_buf(cpu->tcpu, true);
+	else
+		kbuf = tracefs_cpu_buffered_read_buf(cpu->tcpu, true);
 	/*
 	 * tracefs_cpu_buffered_read_buf() only reads in full subbuffer size,
 	 * but this wants partial buffers as well. If the function returns
@@ -274,7 +279,7 @@  static int open_cpu_files(struct tracefs_instance *instance, cpu_set_t *cpus,
 		if (snapshot)
 			tcpu = tracefs_cpu_snapshot_open(instance, cpu, true);
 		else
-			tcpu = tracefs_cpu_open(instance, cpu, true);
+			tcpu = tracefs_cpu_open_mapped(instance, cpu, true);
 		tmp = realloc(*all_cpus, (i + 1) * sizeof(*tmp));
 		if (!tmp) {
 			i--;
@@ -290,6 +295,7 @@  static int open_cpu_files(struct tracefs_instance *instance, cpu_set_t *cpus,
 
 		tmp[i].tcpu = tcpu;
 		tmp[i].cpu = cpu;
+		tmp[i].mapped = tracefs_cpu_is_mapped(tcpu);
 		i++;
 	}
 	*count = i;