disk plugin: Multiply the average read/write latency with the interval.

The counter/derive will later be divided by the interval, resulting in too
small rates (for interval > 1.0).

Should fix issue #150. Thanks to Manuel Sanmartin for identifying this problem!

diff --git a/src/disk.c b/src/disk.c
index 6187459..4a78f1b 100644 (file)
--- a/src/disk.c
+++ b/src/disk.c
@@ -235,6 +235,16 @@ static void disk_submit (const char *plugin_instance,
        plugin_dispatch_values (&vl);
 } /* void disk_submit */
 
+#if KERNEL_LINUX
+static counter_t disk_calc_time_incr (counter_t delta_time, counter_t delta_ops)
+{
+       double avg_time = ((double) delta_time) / ((double) delta_ops);
+       double avg_time_incr = ((double) interval_g) * avg_time;
+
+       return ((counter_t) (avg_time_incr + .5));
+}
+#endif
+
 #if HAVE_IOKIT_IOKITLIB_H
 static signed long long dict_get_value (CFDictionaryRef dict, const char *key)
 {
@@ -579,13 +589,11 @@ static int disk_read (void)
                                diff_write_time = write_time - ds->write_time;
 
                        if (diff_read_ops != 0)
-                               ds->avg_read_time += (diff_read_time
-                                               + (diff_read_ops / 2))
-                                       / diff_read_ops;
+                               ds->avg_read_time += disk_calc_time_incr (
+                                               diff_read_time, diff_read_ops);
                        if (diff_write_ops != 0)
-                               ds->avg_write_time += (diff_write_time
-                                               + (diff_write_ops / 2))
-                                       / diff_write_ops;
+                               ds->avg_write_time += disk_calc_time_incr (
+                                               diff_write_time, diff_write_ops);
 
                        ds->read_ops = read_ops;
                        ds->read_time = read_time;