[PATCH] blktrace: improve live tracing

diff --git a/blktrace.c b/blktrace.c
index 1abafcb44efb63e0785d6e6b2d6e7c2656f22ef8..f9d87eb267c89f491b9cede7deba88384bc71fb5 100644 (file)
--- a/blktrace.c
+++ b/blktrace.c
@@ -143,6 +143,7 @@ struct thread_information {
        pthread_mutex_t *fd_lock;
        FILE *ofile;
        char *ofile_buffer;
+       int ofile_flush;
 
        unsigned long events_processed;
        struct device_information *device;
@@ -394,14 +395,13 @@ static int read_data(struct thread_information *tip, void *buf,
        return 0;
 }
 
-static int write_data(FILE *file, void *buf, unsigned int buf_len)
+static int write_data(struct thread_information *tip,
+                     void *buf, unsigned int buf_len)
 {
-       int ret, bytes_left;
-       char *p = buf;
+       int ret;
 
-       bytes_left = buf_len;
-       while (bytes_left > 0) {
-               ret = fwrite(p, bytes_left, 1, file);
+       while (1) {
+               ret = fwrite(buf, buf_len, 1, tip->ofile);
                if (ret == 1)
                        break;
 
@@ -411,6 +411,9 @@ static int write_data(FILE *file, void *buf, unsigned int buf_len)
                }
        }
 
+       if (tip->ofile_flush)
+               fflush(tip->ofile);
+
        return 0;
 }
 
@@ -594,12 +597,12 @@ static void *extract(void *arg)
                 */
                tip_fd_lock(tip);
 
-               if (write_data(tip->ofile, &t, sizeof(t))) {
+               if (write_data(tip, &t, sizeof(t))) {
                        tip_fd_unlock(tip);
                        break;
                }
 
-               if (pdu_data && write_data(tip->ofile, pdu_data, pdu_len)) {
+               if (pdu_data && write_data(tip, pdu_data, pdu_len)) {
                        tip_fd_unlock(tip);
                        break;
                }
@@ -634,6 +637,7 @@ static int start_threads(struct device_information *dip)
                if (pipeline) {
                        tip->ofile = fdopen(STDOUT_FILENO, "w");
                        tip->fd_lock = &stdout_mutex;
+                       tip->ofile_flush = 1;
                        mode = _IOLBF;
                        vbuf_size = 512;
                } else {
@@ -650,6 +654,7 @@ static int start_threads(struct device_information *dip)
                                        dip->buts_name, tip->cpu);
                        }
                        tip->ofile = fopen(op, "w");
+                       tip->ofile_flush = 0;
                        mode = _IOFBF;
                        vbuf_size = OFILE_BUF;
                }