Showing posts with label speed. Show all posts
Showing posts with label speed. Show all posts

Wednesday, June 17, 2020

Raspberry PI 3 Model B Rev 1.2 Power Wattage

My order of USB power meter arrived a few days ago, but only today I could put it into use by plugging it in between the power supply adapter and my RPI.

The way I test the max power consumed is by creating a small C program to do infinite loop such as:

int main()
{
   while (1) {}
}

I executed it in four separate processes (open four terminals, and run the program in each one). This way I could exhaust the whole four cores in the CPU.  I also GUI desktop on the machine (LXDE).

Here what is shown by "top":




My USB power meter shows 1.17 WH, meaning in each hour it consumes 2.37 Watt or 0.00237 KWh.  If the price per kWh charged by Utility company is 12.01 cent ($0.1201/KWH), in a day I'd pay 0.00237 KWh* $0.1201/KWh * 24 hours = $‭0.006831288‬ or about $0.0068 per day.  In a month I'd pay about $0.2 minimum.

After I killed all those four infinite loop processes, the wattage did not drop.  Instead I saw it climbed to almost 2 Watt-hour.  I think over time it probably would drop back to around 2 W (idling time).

Monday, December 16, 2013

Why we need to migrate to IPv6 sooner



The test result above was done using DOCSIS 3.0 modem, XFinity Blast and thru 5 MHz Wi-Fi (802.11n).
See how IPv6 improves the download speed more than 3 times of IPv4 in download test?

I think of the reason is that with IPv6, we no longer need NAT on the router.  So the router most likely bypassed the traffic and directly forward it from the server to my computer (using global IP address).

The latency also improves with IPv6.  This might be caused due to the fixed size of IPv6 header, unlike IPv4.  All other optional headers in IPv6 are moved beyond the header, so routers can forward packets faster.