rakshasa/rtorrent — Issue #12: Choke Manager slows uploads during downloads?
Author: ntg
Created: 2011-12-06 01:09:47+00:00
State: open

I have seen a definite pattern where *all* uploads run slowly until a torrent is 100% complete. Before the torrent is complete, the upload speeds are often (slightly) higher than the downloads, but they could clearly be uploading much faster. One of the clearest examples is on the "typical" Chinese HD sites with hundreds of peers and slow-downloading torrents (eg CHD, BHD, HDC): the download obviously can't go any faster but the uploads easily could. Then, as soon as the torrent finishes, I see an instant spike in upload speeds of 5-500%, depending on the peers remaining. The same thing happens even on small, fast-moving torrents from sites where most peers are local (eg BTN, SCC, GFT and many others)

My guess is that the choke manager is limiting upload speeds by giving priority to downloads until the torrent is 100% complete. This is normally a good algorithm but if downloads can't saturate the bandwidth then the uploads still seem to be throttled, wthich is just a waste. Even if this isn't the cause, do you have any theories or even better, a fix?

I'm using svn1272 but AFAIK none of this code has changed since before that.