From: Jens Axboe <axboe@kernel.dk>
Date: Thu, 1 Dec 2011 14:17:24 +0000 (+0100)
Subject: Only log the period mean if we have samples
X-Git-Tag: fio-1.99.13~1
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=7fb28d3661a5833d8be24a014a04ee4548ec1c16

Only log the period mean if we have samples

We can't use the mean value to determine that, it could in theory
be 0.0 and still have valid samples.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/stat.c b/stat.c
index 7de23621..c921f5f4 100644
--- a/stat.c
+++ b/stat.c
@@ -1145,11 +1145,17 @@ static void __add_log_sample(struct io_log *iolog, unsigned long val,
 	iolog->nr_samples++;
 }
 
+static inline void reset_io_stat(struct io_stat *ios)
+{
+	ios->max_val = ios->min_val = ios->samples = 0;
+	ios->mean.u.f = ios->S.u.f = 0;
+}
+
 static void add_log_sample(struct thread_data *td, struct io_log *iolog,
 			   unsigned long val, enum fio_ddir ddir,
 			   unsigned int bs)
 {
-	unsigned long elapsed, this_window, mr, mw;
+	unsigned long elapsed, this_window;
 
 	if (!ddir_rw(ddir))
 		return;
@@ -1170,20 +1176,34 @@ static void add_log_sample(struct thread_data *td, struct io_log *iolog,
 	 */
 	add_stat_sample(&iolog->avg_window[ddir], val);
 
+	/*
+	 * If period hasn't passed, adding the above sample is all we
+	 * need to do.
+	 */
 	this_window = elapsed - iolog->avg_last;
 	if (this_window < iolog->avg_msec)
 		return;
 
-	mr = iolog->avg_window[DDIR_READ].mean.u.f;
-	mw = iolog->avg_window[DDIR_WRITE].mean.u.f;
+	/*
+	 * Note an entry in the log. Use the mean from the logged samples,
+	 * making sure to properly round up. Only write a log entry if we
+	 * had actual samples done.
+	 */
+	if (iolog->avg_window[DDIR_READ].samples) {
+		unsigned long mr;
 
-	if (mr)
+		mr = iolog->avg_window[DDIR_READ].mean.u.f + 0.50;
 		__add_log_sample(iolog, mr, DDIR_READ, 0, elapsed);
-	if (mw)
+	}
+	if (iolog->avg_window[DDIR_WRITE].samples) {
+		unsigned long mw;
+
+		mw = iolog->avg_window[DDIR_WRITE].mean.u.f + 0.50;
 		__add_log_sample(iolog, mw, DDIR_WRITE, 0, elapsed);
+	}
 
-	memset(&iolog->avg_window[DDIR_READ], 0, sizeof(struct io_stat));
-	memset(&iolog->avg_window[DDIR_WRITE], 0, sizeof(struct io_stat));
+	reset_io_stat(&iolog->avg_window[DDIR_READ]);
+	reset_io_stat(&iolog->avg_window[DDIR_WRITE]);
 	iolog->avg_last = elapsed;
 }