Activity Monitor Network Wrong "Data sent" calculation

[idark77]

During last week I was monitoring my "Transfer File Speed" and I used Activity Monitor - Network Tab to view my network statistics etc...
I found that Activity Monitor doubles the "Data sent/sec" numbers and it also adds a few MB/sec on top of that!

Please can you also try to copy a file over network and look at Data sent? Or can you try to do a speed test over internet and look at the Data sent/sec number?
For example during my Internet Speed Test I had 20Mbits/sec of Upload (https://www.speedtest.net/ and this value is correct ) but Activity Monitor showed 5-7MBytes/sec (so It was equal to 40-56Mbits/sec)...

Searching Google I found this website https://thehouseofmoth.com/apple-has-been-lying-to-me-for-years/ and this guy had the same problems.

Please can you check your Activity Monitor Network Tab?

My MBP is connected through WiFi 802.11AC (1300Mbs Rate).

 

[Howard2k]

I have a 2.03 GB file on my NAS I'm going to move to local and back. Resarting the test after confirm that Time Machine has finished the backup

Before
12.37GB Rcvd
28.64GB Sent

After moving 2.03GB file to local:
14.35GB Rcvd
28.65GB Sent

Moving back to NAS:
Before:
14.35GB Rcvd
28.65GB Sent

After
14.38GB Rcvd
30.64GB Sent

So it appears pretty close the second time. Lower than I expected to be honest, with protocol overhead.

Also 802.11ac 3x3.

 

[idark77]

Thanks for your test, but I was speaking about speed "Data sent/sec". Can you also check the MB/sec during your test? I see that my throughput is double (and more) when transfer files to my NAS. ( example: My NAS shows 30MB/sec but Activity Monitor Data sent/sec shows 70MB/sec or more ).
Can you read the speed?
Thanks

 

[Howard2k]

Apologies, totally misread that. Yes, stats look misleading.

But in terms of actual time, the 2GB file was moved over from the NAS to the local drive in 32 seconds, so that's just over 500Mb/s, or 63MB/s. Moving the other way was 29 seconds, so 70MB/s.

Some comparison images showing throughput in each direction.

 

[Howard2k]

A quick non-scientific test seems to show that a 1 second update interval gives a result that is closer to reality.
It might be that the traffic is quite bursty and the calculation in Activity Monitor is doing some generous extrapolation?

 

[idark77]

Thanks for your feedback. I also changed the update interval to 1 second in Activity Monitor but the results are always wrong (Higher)... I try to investigate this issue but I suppose that Apple should fix it.

 

[idark77]

Another guy wrote about the same issue:

Accuracy of "Data Sent/sec" in Activity Monitor on MacOS Catalina

I have a 2018 MacBook Pro i7 running MacOS Catalina 10.15.3. I'm uploading a 4.88 GB video to YouTube, using the YouTube Studio web interface in Google Chrome 79. My MacBook Pro is connected to my ...

apple.stackexchange.com

Can anybody else check in its Mac?

 

[sylvercloud]

I had observed this with my new M1 mac. The reported upload/download speed is more than twice the real speed (that I can calculate by timing the file transfer).

 

[idark77]

Using macOS Monterey (MBP Intel) I don’t see this problem anymore.

 

[Enjoylife1788]

I still see the same problem on my M1 MBA. Its mind boggling that Mac has an issues like this.

 

[ziimen]

M1 Pro macbook.... data sent reports exactly double the actual speed... 20mbps upload gets reported as 40mbps.