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Ethernet problems when CPU is not being used


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I've run perfmon, I think the image below shows the problem pretty well!

perfmon.jpg

As for Wireshark, there is a slight problem. Capturing the packets introduces enough load on the CPU that the packet errors do not occur.

I'm not sure if it is a problem with the Intel network card, as the same thing happens with an ExpressCard adapter with a Marvell chipset.

Alex

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Yeah that definetly shows it! :wacko:

Can you run Wireshark without Prime95 and maybe see these errors?

You could set the numproc to 1, or try moving Prime95 to a different core and see if these errors still happen.

I think another thing to consider, besides the "cpu effect", is you're getting too many errors to begin with.

I would definetly want to know what Intel says about this.

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Yeah that definetly shows it! :wacko:

Can you run Wireshark without Prime95 and maybe see these errors?

You could set the numproc to 1, or try moving Prime95 to a different core and see if these errors still happen.

I think another thing to consider, besides the "cpu effect", is you're getting too many errors to begin with.

I would definetly want to know what Intel says about this.

I did run Wireshark without prime, but the CPU load of capturing the packets prevents the errors from occurring.

Also for the test in the perfmon screenshot, I only run Prime95 on one core, that's why the CPU usage only goes up by 25%. It's maxing out one core of a quad core laptop.

I know I'm getting too many errors to begin with, it should be practically nothing. The issue with the CPU only adds to the weirdness.

Alex

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Well in previous post I suggested trying to load a different core, or have Windows only use one core using the numproc setting in msconfig. I am leaning towards the NDIS drivers, though you have tried different ones - quad cores are still rather new. This might have something to do with RSS - I would suggest going to Vista SP2 to see if things change. BTW are these x86 or x64 machines (it could affect the drivers)?

You could try to disable RSS using

netsh interface tcp set global rss=disabled

Can you describe in more detail the 'test' you are doing. For example I tried to replicate your experience by streaming a bluray movie between two of my pcs on a gigabit connection.

I am not familiar with the other counters availible in Performance Monitor, but you may want to read the descriptions of these: 'IPv4', 'Per Processor Network Activity Cycles', and 'Per Processor Network Interface Card Activity'. You could do a shotgun approach and just add all of those counters and look for weird behavior. You can also add counters from the other PC so they appear in the same graph.

I am really anxious to get the Windows Internals 5th edition book, only 12 more days! :P

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I have tried loading different different cores, it doesn't seem to matter which is loaded as long as one is.

I'll have a go tomorrow at turning RSS off and running perfmon with a few more counters and seeing if anything weird shows up.

The machines are both running the 32-bit versions of windows.

The simplest test I've been doing is using the Network test option in Performance Test 7 from Passmark software to stream packets over a TCP connection from one machine to another, and watching the number of packet errors in perfmon. The reason I'm using this software is that I wanted to make sure that the problems still showed up when using third-party software rather than something I had written that may have had a bug in it. Also, it's easy for someone else to try the same software as it has a 30 day evaluation available.

The packet size seems to make a difference. If I set the packet size to 3000 bytes, I get very large numbers of errors, but if I set it to 3072 (ie 3K), I get very few, if any errors. The MTU size is 1460 so neither 3000, nor 3072 is a multiple.

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Right,

Sorry for the delay, I've only just managed to get my hands on the HP laptop again.

I had already tried turning RSS off in the advanced driver settings before you suggested it. I've now tried turning it off by using netsh. Neither way makes any difference.

I guess I'll just have to try getting hold of Intel technical support, but I won't hold my breath on that one.

Alex

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