Better use of available bandwidth (another POV)

[BZFlagLEGOManiac]

Further to my previous post about requesting a feature that would dynamically try different torrents in order to find a combination that maximizes bandwidth utilization, there is another approach.

I'm currently trying to download a 55GB file that currently has 58 seeds and 1198 peers.

I'm on a connection that allows 450Kb downloads.

I'm currently getting a whopping 25Kb transfer rate.

Of course I realize that these people could be using dial-up for all I know or their ISP's may be limiting their bandwidth, but, it's a safe bet that with over 1200 PC's to choose from there has to be some combination that's going to provide better throughput than that.

So, would it be possible to have uTorrent try a different group of peers if the transfer rate/#peers is (say) < .1. I realize this is supposed to happen automatically as part of the bittorrent protocol, but I've been watching this thing for almost an hour now and it needs a severe shake-up, not the slow rate at which peers are being dropped and replaced.

[hermanm]

> transfer rate/#peers is (say) < .1

Can you provide an example please? I understand what you're suggesting, but the math you're suggesting for this is not clear.

Part of the issue is that it seems many Bittorrent users are port blocked, or are spreading their upload speed very thin. From personal experience, a 58:1998 seeder:leecher will generally be slow unless you can connect to and receive from a fast peer by chance. Your chances of having a fast download experience would happen more often if the seeder:leecher ratio is favoring the seeder. I'm generalizing here and this is just from personal observation.

[Switeck]

I have a feeling your ISP is on this list:

http://www.azureuswiki.com/index.php/Bad_ISPs#Canada

Bell Canada (Sympatico) possibly?

Have you tried this?:

http://www.azureuswiki.com/index.php/Avoid_traffic_shaping

Question:

What combination of internet lines do you have to get 405 megabits/second download?

Some kind of crazy experimental fiber lines?

[The8472]

From personal experience, a 58:1998 seeder:leecher

That's not correct. You can get decent speeds on almost any torrent, regardless of seeds:peers ratio if you have a decent upload.

[thelittlefire]

So you made a separate thread because you couldn't double-post in the original one? I max 6Mbit with 20 connected peers. You people connecting to 100s or even 1000s of peers are shoving NEEDLESS overhead down your pipe.

[hermanm]

> That's not correct. You can get decent speeds on almost any torrent,

> regardless of seeds:peers ratio if you have a decent upload.

By decent you mean 25 kB/s. You are referring to decent speeds from Azureus? µTorrent?

[BZFlagLEGOManiac]

A couple of comments to the replies so far.

- As someone noticed, I made an error. I meant to type 450Kb not Mb.

- I started this as a separate thread because the feature would be differnent.

In my original post I was talking about having uTorrent try differnet torrents so it

wouldn't get hung up on dead ones or torrents with no seeds where everyone is

sitting at 76.1% and so are you, hence the system goes the whole day without

downloading anything. I suggested having uTorrent give up and try a different torrent

In this message thread, I was suggesting that, if you get hung up with a slow

connection on ONE torrent, where there are loads of peers or seeds to choose from

force uTorrent to try different peers or seeds to see if the transfer rate can be

improved. After all, if you've got 100 peers and you happened to get the 5 that are

on dial up, uTorrent could probably improve things by tring someone else. This

probably happens automatically somewhere along the line, but I wondered if there

was a way to force the change sooner.

- > transfer rate/#peers is (say) < .1

Don't get too hung up on my math. I haven't thought this through too thoroughly.

I was trying to convey the idea that if you have a torrent with 6 peers and you're

connected to 5 of them and you're getting a transfer rate of 10Kb/s, there's not

much of a chance that if you drop one of them and try the 6th peer that uTorrent

would be able to improve things too much.

On the other hand, if you're connected to 5 peers out of 100 with a 10Kb transfer

the probability at least some of the other 95 peers could offer a better connection

is a lot higher. I wish I'd paid more attention in statistics class, but I trust you get

the idea.

- Switeck - as mentioned, the 450MB reference was a typo. Yes, it's bell sympatico.

DSL speed tests conducted during the setup of uTorrent (and at other times)

show that my connection is a fairly reliable 5Mb line. With a lot of *manual* tweaking

(the subject of this and it's sister thread) I can usually exceed 350Kb transfers with

the right combination of torrents. I can force different sets of peers (the subject of

this thread) by stopping a torrent, waiting, and re-starting it. On a good day, I can

approach 430 to 450Mb transfers. I just wish uTorrent would do the tweaking when

I'm not around. I can only get this kind of performance on the weekend and only if I

park myself in from of the PC and monitor the torrent performances.

- >That's not correct. You can get decent speeds on almost any torrent, regardless of

> seeds:peers ratio if you have a decent upload.

In Theory, yes, but ONLY if the combination of selected peers can upload at a

decent rate. As I said, if you happen to connect to 5 peers who are using dial-up

you've got a good chance of doing better if uTorrent would just shop around instead

of being satisfied with the connections it has. In fairness, there's probably some kind

of mechanism within the bittorrent specs to compensate for this but I was wondering

if uTorrent could be made to force the issue when the number of available peers is

large but the transfer rate is disproportionately small. I know we're playing a

probabilities game here but it may be doable.

- > You people connecting to 100s or even 1000s of peers are shoving NEEDLESS

> overhead down your pipe

That's precisely my point. uTorrent doesn't connect to 1000 peers when they are

available for the exact reason you gave. It connects to only a few, but what if they

are slow connections when there may be many, many more to choose from?

My feature request in this thread was that uTorrent should "shop around" more when

the connection speed is low and the peer count is high.

This ability to try other peers probably already exists within the bittorent protocol, but, as I mentioned in my original message, I had a 25Kb total connection with over 1200 Peers to choose from. Clearly there was a high probability that there would be a better combination of peers out there yet, for a good 10 - 15 minutes uTorrent stayed with the group that it had. That's why I thought uTorrent should have an option enabling it to "shop around" when ratio of speed to peers is clearly very low.

[hermanm]

> I had a 25Kb total connection with over 1200 Peers to choose from.

There are ~1200 peers, but does not mean you can connect to 1200 peers. Many are busy, full, and don't want to talk to you. Your actual available pool is less than 1200.

So, if I understand you correctly... you want µTorrent to be more aggressive about connecting to new peers if your download rate is below a certain transfer rate. What happens if you go through all 1200 peers and your download rate is still slow? You've used all those network resources for no gain.

[Switeck]

I would expect upload speed to be less than download speed...so are you downloading faster than you're uploading?

(Naturally, you'll make up the difference while seeding.)

[BZFlagLEGOManiac]

It's an asymetric DSL (ADSL) line, so, yes - download speed is faster than upload speed. I've just tested it this morning. I'm currently getting 3550Kb/s down and 375Kb/s up

When you think about it, most DSL customers (home users) are just browsing the web and hence, a click on a link sends a small amount of data to the web server but gets a large amount of data in return. Hence the DSL provider gives you, say, a 4Mb/s connection but tweaks it to provide a 90:10 or 80:20 download/upload ratio.

As for hermanm's comment:

> There are ~1200 peers, but does not mean you can connect to 1200 peers. Many

> are busy, full, and don't want to talk to you. Your actual available pool is less than

> 1200.

<snip>

> What happens if you go through all 1200 peers and your download rate is still slow?

> You've used all those network resources for no gain.

You're stating the obvious here. We all know that many of those peers will be busy, etc. We all know that at any given moment only a fraction of the 1200 in this real-world example would be available. We all know that, statistically, there is a possibility that you could go through 1200 peers (or the subset that are available to talk to) and not find some combination that will yield a better aggregate connection than the 25Kbps I was sitting at for an hour.

If I haven't made it clear yet, let me state it differently:

We are playing a probabilities game here. If I've got a torrent with 6 peers and the 5 that I'm connected to are giving me a 25Kbps transfer rate, what are the chances that the 6th one will improve things significantly? I should hope it's clear that the chances are pretty slim.

On the other hand:

> What happens if you go through all 1200 peers and your download rate is still slow?

How likely do you think this actually is? Do you seriously believe that with 1200 peers (or the available subset - still likely in the 100's) that you can't improve on 25Kbps?

Can I guarantee that with a pool that large, this won't happen:

> You've used all those network resources for no gain.

No, I can't.

My feature request is that uTorrent use the following (approximate) logic:

Case 1: I've got a slow torrent. There are 10 times more peers available than I'm currently connected to. Therefor, shop around for something better.

Case 2: I've got a slow torrent. There are very few peers and I'm already connected to 80% of them. There's not much point in shopping around.

Case 3: I've got a fast connection. Leave well enough alone.

This message thread/feature request deals with uTorrent's handling of slow connections with large peer pools and the fact that it does nothing to try to improve it's situation when (statistically) there's a good probability that it could.

The sister-thread to this request dealt with the fact that uTorrent can be set to only download 6 torrents at a time (to save bandwidth) but will pointlessly try to download torrents with no available peers, or will try to download a torrent when it already has all the (available) pieces and won't move on to another queued torrent.

Both these feature requests are about enabling uTorrent to recognize when it's spinning it's wheels, and to get it to move on to something else when it is.

[Switeck]

You misunderstood me.

I meant -- are you consistently getting higher download speeds in uTorrent than your upload speeds in uTorrent?

Because if you're downloading faster than you're uploading, you're already beating the odds.

Someone else (probably seeds) has to make up the difference.

[The8472]

It's an asymetric DSL (ADSL) line, so, yes - download speed is faster than upload speed. I've just tested it this morning. I'm currently getting 3550Kb/s down and 375Kb/s up

Well, there is your problem. Most people don't get that bittorrent is a zero-sum game. So on average one can only download as fast one is uploading. If you want to download faster that means someone gets to download slower (or not at all, as a seed).

So if you want "guaranteed" (sortof, on average) high speeds you better get a faster upload and/or motivate people to seed.