Speeding up torrents

Call me slow, but it took me until the weekend to work out why my torrents were running so slowly. (You know, all those Linux distros I keep downloading. Yeah.) Almost always stuck at about 15-20kbps — if that. Sometimes markedly slower.

Having read about problems with the original firmware, I got to the point of flashing my WRT54G router with the very nifty DD-WRT, which is so amazingly cool that I can’t believe some people took the time to develop it for free. Enthusiasm for innovating is a wonderful thing. But that didn’t fix it.

I switched from ABC (“Another BitTorrent Client”) to uTorrent. Which gave me nifty features like scheduling that will help me avoid burning up my peak hours (7am to midnight) traffic quota. (Came perilously close last month to being “shaped” down to dialup speed. Eek!) But that didn’t fix the torrent speed.

Finally I resorted to fiddling with my speed limits in uTorrent. Changed the upload speed from unlimited down to 20kbps and suddenly the download I was on jumped to 35kbps. Brought the upload down to 15kbps and the download leapt again to 60-70kbps. Eureka!

Dropping the upload to 10 didn’t really affect it further. And by that point I was happy with the speed, so I left it at 15.

See, I’d been going with the principle that it was good to uncap your uploads, to share everything around. What I’ve now learnt is that it’s a good idea to cap them while downloading, and set no limit for once the download has finished. And with the scheduler in uTorrent, you can also tweak things so that most of your downloads happen in off-peak periods at night, but uploads can keep on pumping all the time. (With appropiate caution if you use an ISP that charges for uploads; happy to say mine doesn’t.)

Why don’t they explain this stuff when you start? I guess there’s a bunch of complex stuff to explain to beginners. Mind you, if I’d actually read the documentation, that might have helped.

There’s some other things you can do to optimise Torrents, including patching and fiddling with the Windows XP TCP configuration and lots of other tweaking.

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One thought on “Speeding up torrents

  1. brad

    The reason for this is due to the fact that the “ack” packets which tell the other party in the connection you have received the data have to stand in line with the other upload packets, causing the delay. You can make ack packets jump the the head of the line (using traffic shaping on linux and cisco routers, not sure if the plain ole linksys routers will do it) but that has its issues too (like being hit w/ an attack).

    Brad.

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