Prioritizing Traffic in Remote Desktop

You can control how Terminal Services manages display data

Well it’s the last day of the month and I thought we might wind down our discussion of process prioritization with a tip that might be useful for those of us who use Remote Desktop (a.k.a. Terminal Services client) – which seems to be more and more people these days, as Remote Desktop has continued to get better and more flexible over the years. For most Remote Desktop users, display responsiveness is Job 1. Watching our screens repaint is the most frustrating thing about remote server administration. On the other hand, if you do a lot of file copying and/or printing, then perhaps you don’t care as much about the display’s responsiveness, and in fact you may wish to dial it down a notch in favor of non-display I/O activity. So now you think I’m about to tell you which process to modify in Task Manager (or one of the other prioritization tools we’ve mentioned this week), right? Not this time! It’s even more fun than that. You get to use everybody’s favorite tool, REGEDIT! (One of these days I’m going to do a nice thorough job of raking Microsoft over the coals for continuing to make this the worst administrative tool in the history of computing, but not today.) So stroll on over to your Terminal Server, make sure everything is backed up (at least the system state), and nod your head for the zillionth time that modifying the Registry is a Very Dangerous Thing and silently acknowledge that you will not hold me or my heirs responsible if you screw it up. Then navigate to HKLM – SYSTEM – CurrentControlSet – Services – TermDD. Here you may see several values of type DWORD; the ones we’re interested in are FlowControlDisplayBandwidth and FlowControlChannelBandwidth. If they don’t exist, you can add ‘em. The defaults are 70 and 30, respectively, meaning that the standard behavior is to give display I/O 70% priority and everything else 30%. You can tweak this to a different ratio according to your needs and experiences. I find it easiest if the two numbers add up to 100. Reboot your terminal server and experiment with your new settings.

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