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Ah yes, Bit Torrent. The idea is simple; every download client is also
an upload server. And by sharing the load in this way, each client has
hundreds or even thousands of possible servers to choose from, and can
select the one with the best transfer rate from their location.
There's a big long paper about how all this works, but we can summarise
as follows:
- Every downloader is also an uploader.
- Each downloader connects to multiple uploaders.
- Downloaders try to download from the fastest uploader [from their
location on the network].
- Uploaders upload fastest to the peers they download fastest from.
Thus, hypothetically, the faster you upload, the faster you can
download. This encourages fairness.
- In the interests of fairness, once you've fully downloaded a file,
you're supposed to leave the torrent running for a while so that others
can download it from you.
Tools like Azureus even keep a track of your "share rating" for each
file, and a total rating. The better your share rating, the more you're
helping to seed the torrents you've downloaded.
Now, here's where it all falls apart:
- I have ADSL. That stands for ASYMMETRIC Digital Subscriber Line. In
laymen's terms, by download rate is about 5x faster than my upload rate.
I can download at the speedy rate of around 310 KB/sec, but I can only
*upload* at a maximum of about 46 KB/sec.
- This means that it is physically impossible for me to upload
particularly fast. That should hypothetically result in low download speeds.
- As it happens, seeders by definition don't download anything. So they
can't upload to others based on how fast they download form them. They
therefore upload to the fastest clients. So I still get a nice download
rate.
- However, this means that by the time I've downloaded a file, by share
rating for that file is about 1%.
- No problem, I can just leave the torrent running for a while...
- But wait! This torrent has 450 seeders and 3 downloaders. And I
sometimes see 200 KB/sec from a single seeder, so... why THE HELL is any
peer going to download from me at a piffling 40 KB/sec when there are
peers out there at least 5x faster?
- In short, I typically get upload rates of about 2 KB/sec (while
downloading or seeding). [No, I'm not firewalled.]
- The whole share rating thing is a bit short-signed too. If I upload
10MB to a 100MB torrent, I get a 10% rating. If I upload 100MB to a
1,000MB torrent... I get a 10% rating. In one case I've helped way, way
more, but I still get the same rating.
- More grave: If I upload 100MB to a 500MB torrent with 100 seeders and
3 downloaders, I get a 20% rating. If I upload 100MB to a 500MB torrent
with 3 seeders and 100 downloaders, I have helped out way, way more. But
I still only get a 20% rating.
In short, my ability to give is vastly smaller than my ability to take.
Not because I'm greedy, but because of the underlying technology. And BT
software rates me on how much data I upload, rather than on how helpful
I'm actually being. So Azureus is doomed to sit there for weeks
uploading 2 KB/sec to torrents that probably don't need the help anyway
just so my global share rating can approach unity...
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Orchid XP v8 wrote:
> And BT software rates me on how much data I upload,
You're aware that the share ratio isn't actually part of the protocol,
right? Nobody is keeping track of that except you and perhaps some private
trackers out there?
--
Darren New, San Diego CA, USA (PST)
Forget "focus follows mouse." When do
I get "focus follows gaze"?
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Orchid XP v8 wrote:
> - I have ADSL. That stands for ASYMMETRIC Digital Subscriber Line. In
> laymen's terms, by download rate is about 5x faster than my upload rate.
> I can download at the speedy rate of around 310 KB/sec, but I can only
> *upload* at a maximum of about 46 KB/sec.
>
> - This means that it is physically impossible for me to upload
> particularly fast. That should hypothetically result in low download
> speeds.
>
> - As it happens, seeders by definition don't download anything. So they
> can't upload to others based on how fast they download form them. They
> therefore upload to the fastest clients. So I still get a nice download
> rate.
>
> - But wait! This torrent has 450 seeders and 3 downloaders. And I
> sometimes see 200 KB/sec from a single seeder, so... why THE HELL is any
> peer going to download from me at a piffling 40 KB/sec when there are
> peers out there at least 5x faster?
The wikipedia article mentions some aspects of BT that specifically take
this into account.
> - The whole share rating thing is a bit short-signed too. If I upload
> 10MB to a 100MB torrent, I get a 10% rating. If I upload 100MB to a
> 1,000MB torrent... I get a 10% rating. In one case I've helped way, way
> more, but I still get the same rating.
But in all technicality, you've helped exactly the same, relative to the
whole torrent. Which is the only relevant measure.
--
Tim Cook
http://empyrean.freesitespace.net
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BTW, it was also designed for things like game patches, where you have
gazillions of people all downloading at once, with only a trickle of
interest after the initial flood of downloads.
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Darren New wrote:
> You're aware that the share ratio isn't actually part of the protocol,
> right?
Sure. I just feel like a bit of an arsehole downloading all this stuff
and then not giving anything back, that's all. :-}
...OK, I am officially weird.
[But also, the mathematics of the system is non-optimal. I hate
non-optimal!]
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Orchid XP v8 wrote:
> Darren New wrote:
>> You're aware that the share ratio isn't actually part of the protocol,
>> right?
>
> Sure. I just feel like a bit of an arsehole downloading all this stuff
> and then not giving anything back, that's all. :-}
I have a 900MB torrent up to share ratio 12.
Why not? I have no monthly bandwidth caps.
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On Sun, 17 Jan 2010 18:18:53 +0000, Orchid XP v8 wrote:
> Sure. I just feel like a bit of an arsehole downloading all this stuff
> and then not giving anything back, that's all. :-}
Just leave it run; I usually let my torrents run until either there are 0
peers for an extended period of time or until I hit a share ratio of
1:1. Sometimes I'll let them go longer, but I give priority to those
with a share ratio below 1:1.
Jim
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Orchid XP v8 wrote:
> - I have ADSL. That stands for ASYMMETRIC Digital Subscriber Line. In
> laymen's terms, by download rate is about 5x faster than my upload rate.
> I can download at the speedy rate of around 310 KB/sec, but I can only
> *upload* at a maximum of about 46 KB/sec.
>
> - This means that it is physically impossible for me to upload
> particularly fast. That should hypothetically result in low download
> speeds.
The download speed isn't tied to the upload speed like that. They are
independent.
Besides, the system works well for asymmetric connections like yours.
If a typical ratio of upload to download speed is 10x, then with 10
seeds you can top out your download speed, despite each seeder's upload
speed being low.
> - But wait! This torrent has 450 seeders and 3 downloaders. And I
> sometimes see 200 KB/sec from a single seeder, so... why THE HELL is any
> peer going to download from me at a piffling 40 KB/sec when there are
> peers out there at least 5x faster?
The file is broken up into blocks, you know, rather than transferred
sequentially.
So, the client will download one block from you, while downloading other
blocks from other seeds. You'll still be helping.
...Chambers
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>> - But wait! This torrent has 450 seeders and 3 downloaders. And I
>> sometimes see 200 KB/sec from a single seeder, so... why THE HELL is
>> any peer going to download from me at a piffling 40 KB/sec when there
>> are peers out there at least 5x faster?
>
> The file is broken up into blocks, you know, rather than transferred
> sequentially.
>
> So, the client will download one block from you, while downloading other
> blocks from other seeds. You'll still be helping.
Yes, but the BT algorithm is to try to select the peers which give you
the fastest download rate - to reduce leaching, but mainly so you
download from whichever peers are topologically "nearest" to you.
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Nicolas Alvarez wrote:
> I have a 900MB torrent up to share ratio 12.
>
> Why not?
Becuase it might take several human lifetimes to reach that ratio?
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Jim Henderson wrote:
> Just leave it run; I usually let my torrents run until either there are 0
> peers for an extended period of time or until I hit a share ratio of
> 1:1. Sometimes I'll let them go longer, but I give priority to those
> with a share ratio below 1:1.
Yeah, that's pretty much what I'm doing. It's just that with such a low
upload speed, almost no peers want to talk to you, so it takes an insane
amount of time to reach parity.
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Orchid XP v8 wrote:
> Nicolas Alvarez wrote:
>
>> I have a 900MB torrent up to share ratio 12.
>>
>> Why not?
>
> Becuase it might take several human lifetimes to reach that ratio?
I have been seeding for 11 days.
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>>> I have a 900MB torrent up to share ratio 12.
>>>
>>> Why not?
>> Becuase it might take several human lifetimes to reach that ratio?
>
> I have been seeding for 11 days.
So I'm guessing you have a much faster connection than me?
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Orchid XP v8 <voi### [at] dev null> wrote:
> >>> I have a 900MB torrent up to share ratio 12.
> >>>
> >>> Why not?
> >> Becuase it might take several human lifetimes to reach that ratio?
> >
> > I have been seeding for 11 days.
>
> So I'm guessing you have a much faster connection than me?
I have about your same settings. The largest seeding I've done was about 4.5 or
something.
It doesn't take ages at all: you don't take into account in that formula of
yours the fact that people did not all begin seeding and downloading at the same
time. By the time you begin download, chances are you'll find a few people at
100% and the rest at varying degrees of completion.
Still, I've been able to download at about 300 somethings and seed at about 90
at the same time. It depends on the ratios though.
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Orchid XP v8 wrote:
>>>> I have a 900MB torrent up to share ratio 12.
>>>>
>>>> Why not?
>>> Becuase it might take several human lifetimes to reach that ratio?
>>
>> I have been seeding for 11 days.
>
> So I'm guessing you have a much faster connection than me?
3mbit down, 256kbit up.
I set a 20KB/s limit on BitTorrent upload so it doesn't cause problems for
other Internet activity. Currently it seems to be uploading at a constant
18-20KB/s.
Bumping limit up to 25KB/s... Aaaand it's still uploading at pretty constant
speed, averaging 24.96KB/s.
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Orchid XP v8 wrote:
> - Downloaders try to download from the fastest uploader [from their
> location on the network].
No, downloaders download from multiple uploaders. Not from "the" fastest.
And I don't think torrent clients care about "location on the network" yet.
> - But wait! This torrent has 450 seeders and 3 downloaders. And I
> sometimes see 200 KB/sec from a single seeder, so... why THE HELL is any
> peer going to download from me at a piffling 40 KB/sec when there are
> peers out there at least 5x faster?
Because downloading from 10 seeders who have 40KB/s will get them the file
fast. The "5x faster" peer isn't fast at all if there are already 30 users
downloading from it!
I have the fastest plan my ISP has, and I seed at 20KB/s. Like, constantly;
not random peaks. And I seem to get pretty good download speed.
I have used BitTorrent from a 128kbit upstream connection with little
trouble.
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Nicolas Alvarez <nic### [at] gmailcom> wrote:
> 3mbit down, 256kbit up.
>
> I set a 20KB/s limit on BitTorrent upload so it doesn't cause problems for
> other Internet activity. Currently it seems to be uploading at a constant
> 18-20KB/s.
>
> Bumping limit up to 25KB/s... Aaaand it's still uploading at pretty constant
> speed, averaging 24.96KB/s.
you're mean. I generally limit at 70KB/s. That is fair enough.
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On Sun, 17 Jan 2010 23:57:54 +0100, nemesis <nam### [at] gmailcom> wrote:
> Nicolas Alvarez <nic### [at] gmailcom> wrote:
>> 3mbit down, 256kbit up.
>>
>> I set a 20KB/s limit on BitTorrent upload so it doesn't cause problems
>> for
>> other Internet activity. Currently it seems to be uploading at a
>> constant
>> 18-20KB/s.
>>
>> Bumping limit up to 25KB/s... Aaaand it's still uploading at pretty
>> constant
>> speed, averaging 24.96KB/s.
>
> you're mean. I generally limit at 70KB/s. That is fair enough.
That would be rather counterproductive when the upload capacity of his
Internet connection is only 32 kB/s (in theory; practically, it likely
tops out at 25 or so).
--
FE
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>> - Downloaders try to download from the fastest uploader [from their
>> location on the network].
>
> No, downloaders download from multiple uploaders. Not from "the" fastest.
> And I don't think torrent clients care about "location on the network" yet.
Download speed is used as an approximation for network proximity. And
yes, each machine downloads from multiple peers, but it tries to select
the fastest such peers.
>> - But wait! This torrent has 450 seeders and 3 downloaders. And I
>> sometimes see 200 KB/sec from a single seeder, so... why THE HELL is any
>> peer going to download from me at a piffling 40 KB/sec when there are
>> peers out there at least 5x faster?
>
> Because downloading from 10 seeders who have 40KB/s will get them the file
> fast. The "5x faster" peer isn't fast at all if there are already 30 users
> downloading from it!
Fair enough...
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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> Now, here's where it all falls apart:
>
> - I have ADSL. That stands for ASYMMETRIC Digital Subscriber Line. In
> laymen's terms, by download rate is about 5x faster than my upload rate. I
> can download at the speedy rate of around 310 KB/sec, but I can only
> *upload* at a maximum of about 46 KB/sec.
>
> - This means that it is physically impossible for me to upload
> particularly fast. That should hypothetically result in low download
> speeds.
I don't think it matters does it? My ADSL maximum upload speed is about 45
KB/sec too, but if I let BT use all that then other web browsing etc grinds
to a halt. So I have the global upload rate limited to 32 KB/sec in my BT
client, and downloads still go at 600+ KB/sec if it's a popular file.
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> Yeah, that's pretty much what I'm doing. It's just that with such a low
> upload speed, almost no peers want to talk to you,
So you shouldn't feel bad about just stopping it then.
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>> Yeah, that's pretty much what I'm doing. It's just that with such a
>> low upload speed, almost no peers want to talk to you,
>
> So you shouldn't feel bad about just stopping it then.
I suppose a more pressing point is that I shouldn't feel bad about a
bunch of anonymous IP addresses that I've never even met before. o_O
Damn, I'm pathetic and submissive even online...
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Orchid XP v8 wrote:
My BT client had crashed, but it has 25kBps limit to upload and 100kBps
limit to download (I have 2/0,5Mbps connection). The top file to upload
seems to be openSUSE-11.1-DVD-x86_64-iso (4442,6MB), which has history
of 11654,4MB of upload. I'm honestly surprised that he runner-up is
openSUSE-11.1-DVD-ppc-iso (3934,7MB/9983,7MB). The top ratio goes to
openSUSE-11.1-GNOME-LiveCD-x86_64-iso (681,8MB/5597,3MB, ratio being 8,21).
Just leave it running and let the automation do the tricks :).
-Aero
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On Sun, 17 Jan 2010 18:49:26 +0000, Orchid XP v8 wrote:
> Jim Henderson wrote:
>
>> Just leave it run; I usually let my torrents run until either there are
>> 0 peers for an extended period of time or until I hit a share ratio of
>> 1:1. Sometimes I'll let them go longer, but I give priority to those
>> with a share ratio below 1:1.
>
> Yeah, that's pretty much what I'm doing. It's just that with such a low
> upload speed, almost no peers want to talk to you, so it takes an insane
> amount of time to reach parity.
Not really; I have a 3 Mbps/384 Kbps ADSL line, and while it can take a
week or longer (especially since I throttle my upload speed to 20 KB/s
using SpeedScheduler because otherwise other things I need the line for
slow to a crawl), the method I use seems to work pretty well for me. I
guess it depends on the trackers you're using as well, though, and if
you're pulling recently posted files (I do) or files that are much older
where the number of peers is low to begin with.
Jim
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On Sun, 17 Jan 2010 17:57:54 -0500, nemesis wrote:
> Nicolas Alvarez <nic### [at] gmailcom> wrote:
>> 3mbit down, 256kbit up.
>>
>> I set a 20KB/s limit on BitTorrent upload so it doesn't cause problems
>> for other Internet activity. Currently it seems to be uploading at a
>> constant 18-20KB/s.
>>
>> Bumping limit up to 25KB/s... Aaaand it's still uploading at pretty
>> constant speed, averaging 24.96KB/s.
>
> you're mean. I generally limit at 70KB/s. That is fair enough.
Only if you have a fast enough connection. I measured my connection
(which sounds comparable to Andy's) and figured 80% of that IIRC. So on
the assumption that 20 KB/s is 80% of my measured (not rated) bandwidth
(which ISTR it is), then you're proposing that I'm being "mean" by not
using nearly 300% of my available bandwidth. Are you nuts? ;-)
Jim
Jim
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On Mon, 18 Jan 2010 07:18:44 +0000, Orchid XP v8 wrote:
> but it tries to select the
> fastest such peers.
The point is, though, "fastest such peers" depends on the utilization of
the peers. A peer that has a 3 Mbps upstream connection can perform
worse for you than a peer with a 256 Kbps upstream connection if there
are 50 peers connected to the "faster" peer.
Jim
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