BitTorrent download rate oscillating strangely

This is a discussion on BitTorrent download rate oscillating strangely within the Tech Board forums, part of the Community Boards category; I'm observing some weird behavior in Azureus. My download rate is oscillating with a very definite, fixed period. It is ...

  1. #1
    Captain Crash brewbuck's Avatar
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    BitTorrent download rate oscillating strangely

    I'm observing some weird behavior in Azureus. My download rate is oscillating with a very definite, fixed period. It is synchronized with a similar oscillation in the swarm upload rate. I haven't spent any time getting to know the details of how BitTorrent works -- does anybody know why this is happening?

    I'm not confused because it's oscillating -- I'm confused because it is oscillating with a VERY steady period. Look at this graph:

    http://www.codepsycho.org/brewbuck/bt.png

    I'm connected to 2/12 seeds, 0/12 peers, in case that means anything. Has anybody else ever seen such a regular, oscillating graph? I'm baffled. What the heck could be causing it?

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    CSharpener vart's Avatar
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    is your upload limit big enough? For every 10 downloaded bytes using TCP protocol you sending 1 byte up for approving arrival...
    So 256KBit/sec of download uses about 25kBit of upload...
    If You do not have enough upload bandwidth - upload from any program can greatly decrease the download speed...

    Also you may want to check the stability of the service provided by your internet provider - not always they give you constantly the paid bandwidth, sometimes it flowes due to other user usage sharing the same cabel/gateway
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

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    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by vart View Post
    is your upload limit big enough? For every 10 downloaded bytes using TCP protocol you sending 1 byte up for approving arrival...
    So 256KBit/sec of download uses about 25kBit of upload...
    If You do not have enough upload bandwidth - upload from any program can greatly decrease the download speed...

    Also you may want to check the stability of the service provided by your internet provider - not always they give you constantly the paid bandwidth, sometimes it flowes due to other user usage sharing the same cabel/gateway
    I understand that stuff. What I'm confused about is why the oscillation is so rock-steady. It's like a pacemaker. Did you look at the graph? That's doesn't look like random influences to me.

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    CSharpener vart's Avatar
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    if you don't see correlations with some periodic uploads that happen in your system - you can try to use some sniffer like Ethereal to see some dependencies maybe...

    Or you can switch temporary to another client - like mu-torrent to ensure that this is not your program problem (I really dobt that this is Bit-torrent issue - but to be sure is always nice)
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

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    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by vart View Post
    if you don't see correlations with some periodic uploads that happen in your system - you can try to use some sniffer like Ethereal to see some dependencies maybe...
    But if you look at the graph, the "swarm rate" is oscillating too. The WHOLE SWARM is oscillating at a very steady rate. Very weird. There are not very many seeds available. I wonder if some seed host is oscillating because of something happening on THAT system...

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