[core-dev] New 4.2.4 test results (More tests confirm (re: Bandwidth Balanced Swarms?))

Hi Sam, I have just run the same tests using Limewire 4.2.4 with a fresh install on each system; I un-installed the previous 4.2.3 version, deleted the .limewire folder, and installed 4.2.4. I then downloaded individually from each of my servers, and got nearly full speed from each when they were the only source (that is, for each server I tested how fast it could download by itself before trying them both as sources at the same time). When I downloaded from both, however, the overall speed on each dropped by about 1/2 as reported in my previous tests. As a result, downloading from two sources was no faster than downloading from a single source since the single source downloads run at full speed whereas the multi-source drops off in speed by about half for each new source added. I don't know if it matters at all, but for all of these tests I've been using magnet links and the "as" (alternate source) in particular so that I can specify two different sources fir the download.

Are you able to replicate these tests to see if we're actually seeing the same basic behavior?

I'm happy to help with other tests if you'd like me to do that, and can try to help with code (but not sure where/what to look at!). Hope the current tests shed some light on the problem... Brian

----- Original Message -----
From: "Brian Fall"
To: [email protected]
Subject: Re: [core-dev] More tests confirm (re: Bandwidth Balanced Swarms?)
Date: Mon, 29 Nov 2004 16:49:55 -0500

>
> It sounds like a race condition, Sam, since on all the computers
> that I've been testing on Limewire 4.2.3 has been set to full speed
> (no throttle -- the slider is set to allow unlimited bandwidth as
> you suggest). For a while I thought that it was actually balancing
> the load between nodes intentionally since it was so consistant,
> dropping of more and more with each new source being found, but it
> sounds like there must be another issue if that's not coded into
> Limewire intentionally. I'm happy to help out with more testing and
> some coding as well... Brian
>
>
> ----- Original Message -----
> From: "Sam Berlin"
> To: [email protected]
> Subject: Re: [core-dev] More tests confirm (re: Bandwidth Balanced Swarms?)
> Date: Mon, 29 Nov 2004 11:14:05 -0500
>
> >
> > Hi Brian,
> >
> > This is very interesting ... the slowdown is more or less a race
> > condition in the code and something that should appear only
> > occasionally. This is very odd that you're seeing it all the
> > time. LimeWire, by default, does not throttle downloads.
> > However, you may have added some throttling by changing your
> > options (Options -> Downloads, "Download Bandwidth"). If that
> > slider is set to unlimited, no throttling will take place -- if
> > it's anything less, there may be some throttling. Can you check
> > to make sure the downloads aren't being throttled? If they're
> > not, we'll definitely have to investigate into this.
> >
> > Thanks,
> > Sam
> >
> > On Nov 29, 2004, at 9:59 AM, Brian Fall wrote:
> >
> > >
> > > Hi guys, before trying to address this problem I wanted to test
> > a > little more to ensure that it was actually an issue (and not
> > just a > temporary problem) and can now confirm the problem with
> > more detail. > To test I use Limewire Pro 4.2.3 on a laptop that
> > connected to two of > my own servers that both ran Limewire as
> > well. I used a movie that > only I have (so that no other peers
> > on the network would be found; > just mine for which I could
> > monitor the upload speed) and ran the > tests again, and the
> > results are the same: when downloading from just > one server
> > Limewire would download at nearly full speed (not 100% of > the
> > servers available bandwidth, more like 80% or so but that's
> > fine). > But when I would place the same file on the other server
> > and re-try it > would download at about 50% of the available
> > download speed for each > server -- in fact, downloading from two
> > servers wasn't much faster (if > at all) than downloading from a
> > single server because of the drop-off > in download speed once mo!
> > > re than 1 source was used. When I tried the same tests with a
> > file > that IS available on the larger Gnutella network things
> > got much worse > -- for every new source that my laptop client
> > found I saw a > substantial decrease in download speed from my
> > severs (that is, as > each source was found my own servers
> > dropped off in speed). By the > time I had a handful of sources
> > for the file my own servers had > dropped off to about 5% of
> > their available bandwidth.
> > >
> > > This is such a clean drop-off in download speed (almost by half
> > each > time a new source is added) it makes me think that
> > Limewire does this > intentionally, although you mentioned that
> > it might just be code in > need of an update Sam. I've started to
> > read the downloading source > files, but they're pretty hairy and
> > the changes I've made so far don't > make any impact. I was
> > thinking now of working on the bandwidth > methods, but don't
> > know if that's the right area to focus on for this. > If you have
> > any suggestions of what source files and where in them to >
> > revise I'll do that, as any direction you can give me would be a
> > great > help (right now it's just trial and error, mostly error,
> > and I fear > that I'm heading in the wrong direction with regard
> > to fixing the > problem).
> > >
> > > Brian
> > > ---
> > >
> > >
> > >
> > > I see -- thanks, Sam. I thought that it might be a feature
> > (makes > sense in some ways to balance the node on a public p2p
> > network so that > no one node is overtaxed) and wondered if it
> > would be simple enough to > specify which nodes or IP ranges
> > should download full speed while > leaving the default behavior
> > (balancing) as-is for other nodes. I'll > continue to poke around
> > and see if there's a simple way to do that, > and would be happy
> > to follow your lead if you have ideas on where in > the code to
> > do that... do you think, for example, that making the > download
> > chunk size larger would help at all (just an idea; if the >
> > download chunks are large, coming from my own servers, maybe
> > there > won't be enough time for load to be balanced as other
> > sources are > found... but maybe not, come to think of it, since
> > the download speed > from my servers tapers off as soon as an
> > other source is found so as i > think it through while typing
> > this my guess is that a larger chunk > size won't help....hmmmm!)
> > Brian
> > >
> > > ----- Original Message -----
> > > From: "Sam Berlin"
> > > To: [email protected]
> > > Subject: RE: [core-dev] Bandwidth Balanced Swarms?
> > > Date: Sat, 27 Nov 2004 17:01:39 -0500
> > >
> > > Hi Brian,
> > >
> > >
> > >
> > > I suspect this is a limitation of the way LimeWire synchronizes
> > its > data-structures related to which parts of the file have
> > been > downloaded. If a server is very slow sending a response
> > to a single > request, that request will hold up all other
> > connections from > requesting a new chunk. The downloading code
> > is long overdue for some > re-architecting, to remove these
> > limitations and simplify the class in > general. Unfortunately,
> > I don’t believe this limitation can be > removed without some
> > serious changes to ManagedDownloader and the way > downloading is
> > general is designed.
> > >
> > >
> > >
> > > Thanks,
> > >
> > > Sam
> > >
> > >
> > >
> > > From: [email protected] >
> > [mailto:[email protected]] On Behalf Of Brian
> > Fall
> > > Sent: Saturday, November 27, 2004 4:52 PM
> > > To: [email protected]
> > > Subject: [core-dev] Bandwidth Balanced Swarms?
> > >
> > >
> > >
> > > Hello again -- I posted this to the forums, thinking it was
> > more along > the lines of a question the end user community could
> > help with, but > since I'll want to have full speed from my own
> > nodes I thought I'd > repost here in hopes that I can be pointed
> > in the right direction. > Curently I'm looking in
> > ManangedDownloader and HTTPDownloader to relax > this balancing,
> > if possible. Is that the right place to look? Regards, > Brian
> > >
> > >
> > >
> > > Hello... I can't be certain, but for me (Limewire Pro 4.2.3) it
> > looks > like Limewire is balancing bandwidth between the various
> > sources when > swarming a download. I have tested this with my
> > own server, which > drops in upload speed (to the test client)
> > shortly after the client > finds more sources -- my client starts
> > off downloading at full speed > from my server initially, since
> > its the first source it finds, but > then the upload speed
> > dramatically tapers off once the client finds > other sources.
> > For example, with only my server as the source the > transfer
> > rate is about 100KB, but that drops down to about 5KB once > the
> > client finds other sources.
> > >
> > > Is this how Limewire was designed? I ask because I wanted to
> > use my > own server as the main source (fastest downloads), with
> > only minor > amounts being downloaded from the larger Gnutella
> > network. But no > matter what I try I can't seem to keep a full
> > speed download going > from my server once other sources are
> > available to the client.
> > >
> > > Is there a way to do that?
> > >
> > > With thanks for any insight into the Limewire design you can offer!
> > > Brian
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