Use poll() for avoiding a busy loop to read trace data of a guest from FIFO.
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@xxxxxxxxxxx>
---
trace-recorder.c | 42 ++++++++++++++++++++++++++++++++++++------
1 files changed, 36 insertions(+), 6 deletions(-)
diff --git a/trace-recorder.c b/trace-recorder.c
index 6577fe8..bdf9798 100644
--- a/trace-recorder.c
+++ b/trace-recorder.c
@@ -34,9 +34,12 @@
#include <ctype.h>
#include <errno.h>
#include <stdbool.h>
+#include <poll.h>
#include "trace-cmd.h"
+#define WAIT_MSEC 1
+
struct tracecmd_recorder {
int fd;
int trace_fd;
@@ -235,9 +238,37 @@ static void stop_operation_to_trace_agent(int ctl_fd)
operation_to_trace_agent(ctl_fd, false);
}
-int tracecmd_start_recording(struct tracecmd_recorder *recorder, unsigned long sleep)
+static int wait_data(struct tracecmd_recorder *recorder, unsigned long sleep)
{
+ struct pollfd poll_fd;
struct timespec req;
+ int ret = 0;
+
+ if (recorder->agent_existing) {
+ poll_fd.fd = recorder->trace_fd;
+ poll_fd.events = POLLIN;
+ while (1) {
+ ret = poll(&poll_fd, 1, WAIT_MSEC);
+
+ if(ret < 0) {
+ warning("polling error");
+ return ret;
+ }
+
+ if (ret)
+ break;
+ }
+ } else if (sleep) {
+ req.tv_sec = sleep / 1000000;
+ req.tv_nsec = (sleep % 1000000) * 1000;
+ nanosleep(&req, NULL);
+ }
+
+ return ret;
+}
+
+int tracecmd_start_recording(struct tracecmd_recorder *recorder, unsigned long sleep)
+{
long ret;
recorder->stop = 0;
@@ -246,11 +277,10 @@ int tracecmd_start_recording(struct tracecmd_recorder *recorder, unsigned long s
run_operation_to_trace_agent(recorder->ctl_fd);
do {
- if (sleep) {
- req.tv_sec = sleep / 1000000;
- req.tv_nsec = (sleep % 1000000) * 1000;
- nanosleep(&req, NULL);
- }
+ ret = wait_data(recorder, sleep);
+ if (ret < 0)
+ return ret;
+
ret = splice_data(recorder);
if (ret < 0)
return ret;
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