Differences
This shows you the differences between two versions of the page.
| Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
|
searchwing-pi-datarate [2019/11/27 16:46] beckmanf ssh wlan |
searchwing-pi-datarate [2020/01/08 22:00] beckmanf [Results] |
||
|---|---|---|---|
| Line 327: | Line 327: | ||
| The CPU is fully loaded. 90% of the time is spent in the ssh daemon. This is probably due to the encryption of ssh. The rate is limited by CPU load. For short files the initial transactions probably limit the rate. | The CPU is fully loaded. 90% of the time is spent in the ssh daemon. This is probably due to the encryption of ssh. The rate is limited by CPU load. For short files the initial transactions probably limit the rate. | ||
| + | |||
| + | ==== http transfer via USB ==== | ||
| + | |||
| + | I installed the lighttpd web server on the Raspberry Pi and tested the file transfer via wget. | ||
| + | |||
| + | <code> | ||
| + | Fredo:~ fritz$ wget 192.168.2.2/tf100mb | ||
| + | --2019-11-27 16:52:57-- http://192.168.2.2/tf100mb | ||
| + | Verbindungsaufbau zu 192.168.2.2:80 … verbunden. | ||
| + | HTTP-Anforderung gesendet, auf Antwort wird gewartet … 200 OK | ||
| + | Länge: 100000000 (95M) [application/octet-stream] | ||
| + | Wird in »tf100mb.2« gespeichert. | ||
| + | |||
| + | tf100mb.2 100%[========================================================>] 95,37M 18,6MB/s in 5,2s | ||
| + | |||
| + | 2019-11-27 16:53:02 (18,5 MB/s) - »tf100mb.2« gespeichert [100000000/100000000] | ||
| + | |||
| + | Fredo:~ fritz$ | ||
| + | </code> | ||
| + | |||
| + | It takes 5.2s to transfer the 100MB file. That corresponds to a speed of 153 Mbit/s. The full usb speed according to iperf is used. The transfer times for the 1MB file are 0.06s and for the 3MB file 0.2s. | ||
| ==== iperf measurements via WLAN ==== | ==== iperf measurements via WLAN ==== | ||
| Line 458: | Line 479: | ||
| The CPU is fully loaded and 30% are used for the ssh daemon and 60% are required for the wifi driver. It takes about 55s to transfer the 100 MB file. The rate is therefore around 14 MBit/s. The 1MB files take 0.8s (=10 MBit/s) and the 3MB file takes 2.5s (=10 MBit/s). | The CPU is fully loaded and 30% are used for the ssh daemon and 60% are required for the wifi driver. It takes about 55s to transfer the 100 MB file. The rate is therefore around 14 MBit/s. The 1MB files take 0.8s (=10 MBit/s) and the 3MB file takes 2.5s (=10 MBit/s). | ||
| + | ==== http transfer time for wifi ==== | ||
| + | |||
| + | The results for the wget transfer time are 0.8s for the 1MB file, 1.1s for the 3MB file and 30s for teh 100MB file. However, these measurements were made at 19.00, i.e. there is quite some traffic on channel 1 now... | ||
| + | |||
| + | The transfer times for the 100MB were 30s, 24s, 25s, 26s. This corresponds to a transfer rate of 30 MBit/s. Some times for the 1MB file were: 0.2 0.2 0.2 0.9 0.3 0.7 0.7 0.2 -> There is heavy congestion on channel 1. | ||
| + | |||
| + | Based on the 0.2s for the 1 MB File, this translates to **5 MB/s = 40 MBit/s** rate for an undisturbed channel for a transfer via http. This is again exactly the achieved iperf rate as shown above. | ||
| + | |||
| + | ==== Julian tests ==== | ||
| + | |||
| + | * WIFI Only datatransfer | ||
| + | * Router: FritzBox 7430 AW | ||
| + | * Placement: Pi Zero and Laptop placed 10cm above router. | ||
| + | * data ammount: 540 MByte | ||
| + | * ** Laptop and Raspberry Pi share the same Wifi channel => Each packet goes from Pi to AP and from AP to Laptop. => Congestion on the Wifi Channel. ** | ||
| + | |||
| + | === wget === | ||
| + | * time=213sek | ||
| + | * rate=2.53 Mbyte/sek | ||
| + | * cpuusage=70% | ||
| + | |||
| + | === ftp === | ||
| + | * time=361sek | ||
| + | * rate=1.495 Mbyte/sek | ||
| + | * cpuusage=50-60% | ||
| ==== Results ==== | ==== Results ==== | ||
| + | * The Laptop and the Pi should not be connected via a single 2.4 GHz access point as laptop and Pi share the same Wifi channel. This results in 50% throughput reduction (see Julians 2.5 MB/s for wget). | ||
| + | * The transfer rate via wget on an undisturbed 2.4 GHz wifi channel is **5 MB/s**. (Only Pi connected to AP, No other stations use this channel). This 40 MBit/s throughput on http level compares well to the maximum 65 MBit/s wifi data rate of the Pi Zero W. | ||
| + | * ssh transfer is limited by CPU load on the Pi for encryption and results in 1.8 MB/s for Wifi. | ||
| + | * Short Guard Interval setting could possibly increase the the raw wifi rate from 65 MBit/s to 72 MBit/s. | ||