From: Jens Axboe <axboe@suse.de>
Date: Fri, 21 Oct 2005 12:35:25 +0000 (+0200)
Subject: [PATCH] fio: async latency calculation fixes
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=98168d55aecdfd4ed2683c91a7437834eaa15255;p=disktools.git

[PATCH] fio: async latency calculation fixes
---

diff --git a/fio.c b/fio.c
index ace14b7..8ccf5cc 100644
--- a/fio.c
+++ b/fio.c
@@ -281,6 +281,11 @@ static unsigned long mtime_since(struct timeval *s, struct timeval *e)
 	return sec + usec;
 }
 
+static inline unsigned long msec_now(struct timeval *s)
+{
+	return s->tv_sec * 1000 + s->tv_usec / 1000;
+}
+
 static unsigned long get_next_offset(struct thread_data *td)
 {
 	unsigned long b;
@@ -478,7 +483,8 @@ static void aio_put_iocb(struct thread_data *td, struct iocb *iocb)
 	td->aio_iocbs_status[offset] = 0;
 }
 
-static struct iocb *aio_get_iocb(struct thread_data *td, char *buffer)
+static struct iocb *aio_get_iocb(struct thread_data *td, char *buffer,
+				 struct timeval *t)
 {
 	struct iocb *iocb = NULL;
 	int i;
@@ -499,11 +505,15 @@ static struct iocb *aio_get_iocb(struct thread_data *td, char *buffer)
 			io_prep_pread(iocb, td->fd, p, td->bs, off);
 		else
 			io_prep_pwrite(iocb, td->fd, p, td->bs, off);
+
+		io_set_callback(iocb, (io_callback_t) msec_now(t));
 	}
 
 	return iocb;
 }
 
+#define iocb_time(iocb)	((unsigned long) (iocb)->data)
+
 static void do_async_io(struct thread_data *td)
 {
 	struct timeval s, e;
@@ -532,7 +542,7 @@ static void do_async_io(struct thread_data *td)
 
 		gettimeofday(&s, NULL);
 
-		iocb = aio_get_iocb(td, buf);
+		iocb = aio_get_iocb(td, buf, &s);
 
 		ret = io_submit(*td->aio_ctx, 1, &iocb);
 		if (ret < 0) {
@@ -557,6 +567,8 @@ static void do_async_io(struct thread_data *td)
 		} else if (!ret)
 			continue;
 
+		gettimeofday(&e, NULL);
+
 		for (i = 0; i < ret; i++) {
 			struct io_event *ev = td->aio_events + i;
 
@@ -564,11 +576,23 @@ static void do_async_io(struct thread_data *td)
 			td->aio_cur_depth--;
 
 			iocb = ev->obj;
+
+			msec = msec_now(&e) - iocb_time(iocb);
+			add_stat_sample(td, msec);
+
+			if (msec < td->min_latency)
+				td->min_latency = msec;
+			if (msec > td->max_latency)
+				td->max_latency = msec;
+
 			aio_put_iocb(td, iocb);
 		}
 
-		gettimeofday(&e, NULL);
-
+		/*
+		 * the rate is batched for now, it should work for batches
+		 * of completions except the very first one which may look
+		 * a little bursty
+		 */
 		usec = utime_since(&s, &e);
 
 		rate_throttle(td, usec);
@@ -577,14 +601,6 @@ static void do_async_io(struct thread_data *td)
 			td->error = ENODATA;
 			break;
 		}
-
-		msec = usec / 1000;
-		add_stat_sample(td, msec);
-
-		if (msec < td->min_latency)
-			td->min_latency = msec;
-		if (msec > td->max_latency)
-			td->max_latency = msec;
 	}
 
 	gettimeofday(&e, NULL);