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Bug of the moment 2006-04-20

Every now and again, a bug comes along that is so astoundingly silly that you know that the world is going to be OK and you can be happy.

I had reason to examine my Windows networking throughput and, without wanting to risk the malware-laden rubbish off the freeware sites, I took recourse to the Windows Performance console and created some counters. I read off my upstream from one program as 6 kB/sec but according to Windows I was doing about 2.5. I have never felt like any other software was lying to me about speed before so I tried releasing the throttle; upstream went up to about 23 kB/sec, close to my maximum of 26. With the graph scale set to a y-axis maximum of 26, I was still only getting an upstream of approximately 3 kB/sec:

This was most puzzling … why can’t Windows see more traffic in either direction than 3 kB/sec? Eventually (maybe I need some breakfast) I spotted that Windows also gives you numerical readouts, which are all correct. So if the numbers are correct, what is up with the graph? And then it dawned on me: to convert bytes in kilobytes, you divide by (in generic scale terms) 0.001 (1/1000), not 0.0001 (1/10,000)!

I must confess that I did check the scales – which were provided by default when I added the counters – and didn’t spot that they were whole order of magnitude out. Not that that excuses them for being wrong in the first place. Actually, since the counters are named as “bytes/sec” you would imagine that the default scale factor should be 1, so clearly someone was having a bad day when this was set up. It just so happened that I wanted kilobytes anyway so I subconsciously skipped over this part. Now, at least, I have the correct scales set and the correct display of transfer rate!

But no, I don’t know why the y-axis scale goes up in increments of 2.6 in the screenshot! I’ve set the axis maximum back to 100 and now it increments by 4. D’oh.

Posted 20th April 2006 – Comments and questions?