Search code examples
algorithmtimebandwidth

Speed per second on update interval less than a second

enter image description here

Let's, for example here, look at this widget. It reads from sysfs, more precisely the files:

/sys/class/net/wlan0/statistics/tx_bytes
/sys/class/net/wlan0/statistics/rx_bytes

And displays the bandwidth in Megabits per second. Now, the drill is, the widget is set to update every 1/4 of a second, 250ms. How, can the widget them calculate speed per second, if a second did not pass? Does is multiply the number it gets with 4? What's the drill?

Solution

  • The values read from tx_bytes and rx_bytes are always current. The Widget just has to read the values every 250 ms and memorize at least the last 4 values. On each update, the difference between the current value and value read 1 second ago can be taken, divided by 125.000 and correctly be reported as the bandwidth in Megabits per second.