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PowerBoost and it's implication on BitTorrent upload speed limiting


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Lately, I've had a new confounder to deal with when tweaking my upload speeds. Firstly, if you haven't heard of PowerBoost, it's a feature that is becoming common in areas that Comcast cable is available. It's not everywhere yet, though apparently it will be soon. It doubles your upload/download cap for a specified duration when its' routers detect that you've maxed out either your upload or your download capacity.

This is great news to most people in their service area, but there is somewhat of a problem when you deal with BitTorrent in this situation. If you limit your upload speed to, lets say for a common Comcast plan, 32-35 Kb/s, there is no way for any client at the moment to take advantage of that extra bandwidth available to you; manual tweaking for every download being an unrealistic exception. What's neat about PowerBoost is, it isn't dependent on anything but time, and speed.

This means, that every 5 or so minutes, you can use PowerBoost again for roughly thirty seconds. The implications are that essentially, if it were utilized properly, the users average upload cap could be 1.1-1.5 times their advertised limit.

Although you think I probably did my math wrong, PowerBoost actually tends to triple or quadruple your upload cap, while doubling your download cap. I don't really understand why they'd advertise differently, but it just seems to be the way it works. In fact, in my case, the last time I tested it I got a 5 time increase, from 384k to 1920k. I have had it sextuple once, when it just started in my area, but I think they've capped it at 5x.

So I guess what I'm recommending is a feature that would automatically cycle between a lower upload speed for a specified interval, and then a raised upload speed for a specified interval. Similar to the scheduler, but with relative times, not absolute times.

I know 1.5 times the average upload speed doesn't sound like all of that much, but every bit counts (no pun intended), when you're trying to maintain a decent ratio. Also, I think that this would probably get many Comcast users of other BitTorrent clients to use uTorrent, were it the only one with this feature.

Here's my upload graph to demonstrate:


Just an idea, but I thought it would be a neat idea for uTorrent. Keep up the good work guys.

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If you want it to burst speed every X number of seconds, you set bt.auto_ul_interval to X (in seconds). You can determine how long this unlimiting should run for using bt.auto_ul_sample_window. Now, by setting bt.auto_ul_min and bt.auto_ul_max to some ridiculously low number (both 0, for example), µTorrent will ignore all measured speeds, and won't bother changing the upload limit from the previous limit every time it finishes with the sampling_window.

This is somewhat of an abuse of the feature, though :P By the way, I haven't actually tried this, but it should work if the automatic upload limiting works as I understand it.

Edit: Bah, I'm not really sure -- don't blame me if it doesn't work xD

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The reports I've heard on how PowerBoost works are actually quite different. My concern with tailoring any system to take advantage of it lies there - the parameters could vary wildly enough to make it more harmful to try then not.

That said, we can provide general settings as Ultima mentioned that would allow people to configure uTorrent to take advantage of it for their situation.

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PowerBoost now works in my area, much the same as SargeZT described.

My upload speed briefly zooms upwards from my normal max of 42 KiloBYTES/sec to top out between 200-300 KiloBYTES/sec...though it doesn't seem to sustain that value for more than a second. The upload speed then falls almost as rapidly as it rose back down to the normal max.

To trigger it, I just turn off upload speed limits for a few seconds and then turn it back on quickly once it falls below about 50 KiloBYTES/sec again.

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