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Ashwin Rao | 12 Jul 2010 09:54
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Can Realistic BitTorrent Experiments Be Performed on Clusters?

Hello,

We were among the first one to run large scale BitTorrent experiments
on clusters instead of classical platforms like PlanetLab. Our
argument in favor of a cluster is the scale (we ran up to 10 000
simultaneous real BitTorrent peers, but is is possible to run much
more) and the reproducibility.

However, we received criticism arguing that PlanetLab experiments are
more realistic. PlanetLab offers a large variety of delays and loss
rates but due to virtualization it fails to be realistic.

For this reason, we performed a study to evaluate the impact of delays
and losses on BitTorrent experiments. We found that realistic
BitTorrent experiments can be safely run on clusters. We believe that
this work is relevant for this community. Here is the reference to
this work that has been accepted in the P2P'10
conference:http://hal.inria.fr/inria-00494410/en/

Regards,
Ashwin
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Roger Pau Monné | 21 Jul 2010 18:04
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Metainfo Integers

Hello,

I'm sorry to bother the list with this noob question, but I've read at
http://wiki.theory.org/BitTorrentSpecification that integers in
bittorrent metainfo bencoded files (.torrent) can be 64bit signed
integers, why are they signed? Since it's only used for piece lenght,
number of pieces... It is correct to treat them as 64bit unsigned
integers? Or I am missing something.

Thanks for the help, Roger
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Harold Feit | 21 Jul 2010 19:32
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Re: Metainfo Integers

The BEncode format considers the possibility of non-torrent applications
for storage. There is the potential for other applications to need
negative values to be stored as integers.

Unsigned integers of varying lengths are possible, even beyond 64-bit.
Be prepared to adjust accordingy.

On 21/07/2010 1:04 PM, Roger Pau Monné wrote:
> Hello,
> 
> I'm sorry to bother the list with this noob question, but I've read at
> http://wiki.theory.org/BitTorrentSpecification that integers in
> bittorrent metainfo bencoded files (.torrent) can be 64bit signed
> integers, why are they signed? Since it's only used for piece lenght,
> number of pieces... It is correct to treat them as 64bit unsigned
> integers? Or I am missing something.
> 
> Thanks for the help, Roger
> _______________________________________________
> BitTorrent mailing list
> BitTorrent <at> lists.ibiblio.org
> http://lists.ibiblio.org/mailman/listinfo/bittorrent
> 
>
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Roger Pau Monné | 22 Jul 2010 10:59
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Re: Metainfo Integers

Thanks for the reply. Well since my parser is only used to decode
.torrent files, I think I'm safe using uint64. Also, my programming
language doesn't support anything larger than uint64 (for the time
being).

2010/7/21 Harold Feit <dwknight <at> depthstrike.com>:
> The BEncode format considers the possibility of non-torrent applications
> for storage. There is the potential for other applications to need
> negative values to be stored as integers.
>
> Unsigned integers of varying lengths are possible, even beyond 64-bit.
> Be prepared to adjust accordingy.
>
> On 21/07/2010 1:04 PM, Roger Pau Monné wrote:
>> Hello,
>>
>> I'm sorry to bother the list with this noob question, but I've read at
>> http://wiki.theory.org/BitTorrentSpecification that integers in
>> bittorrent metainfo bencoded files (.torrent) can be 64bit signed
>> integers, why are they signed? Since it's only used for piece lenght,
>> number of pieces... It is correct to treat them as 64bit unsigned
>> integers? Or I am missing something.
>>
>> Thanks for the help, Roger
>> _______________________________________________
>> BitTorrent mailing list
>> BitTorrent <at> lists.ibiblio.org
>> http://lists.ibiblio.org/mailman/listinfo/bittorrent
>>
>>
(Continue reading)

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Alan | 22 Jul 2010 12:44
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Re: Metainfo Integers

No, you're not safe at all. Anyone can put a negative number in a .torrent file and for any reason and you will encounter this in the wild. Why would you even want to treat bencoded numbers as being unsigned when the spec clearly says they are signed?

Alan

On Thu, Jul 22, 2010 at 9:59 AM, Roger Pau Monné <royger <at> gmail.com> wrote:
Thanks for the reply. Well since my parser is only used to decode
.torrent files, I think I'm safe using uint64. Also, my programming
language doesn't support anything larger than uint64 (for the time
being).

2010/7/21 Harold Feit <dwknight <at> depthstrike.com>:
> The BEncode format considers the possibility of non-torrent applications
> for storage. There is the potential for other applications to need
> negative values to be stored as integers.
>
> Unsigned integers of varying lengths are possible, even beyond 64-bit.
> Be prepared to adjust accordingy.
>
> On 21/07/2010 1:04 PM, Roger Pau Monné wrote:
>> Hello,
>>
>> I'm sorry to bother the list with this noob question, but I've read at
>> http://wiki.theory.org/BitTorrentSpecification that integers in
>> bittorrent metainfo bencoded files (.torrent) can be 64bit signed
>> integers, why are they signed? Since it's only used for piece lenght,
>> number of pieces... It is correct to treat them as 64bit unsigned
>> integers? Or I am missing something.
>>
>> Thanks for the help, Roger
>> _______________________________________________
>> BitTorrent mailing list
>> BitTorrent <at> lists.ibiblio.org
>> http://lists.ibiblio.org/mailman/listinfo/bittorrent
>>
>>
>
_______________________________________________
BitTorrent mailing list
BitTorrent <at> lists.ibiblio.org
http://lists.ibiblio.org/mailman/listinfo/bittorrent

_______________________________________________
BitTorrent mailing list
BitTorrent <at> lists.ibiblio.org
http://lists.ibiblio.org/mailman/listinfo/bittorrent
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Jon Bellamy | 22 Jul 2010 15:28
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Re: Metainfo Integers

If the spec says use to use an s64 then you should use an s64. Doing anything else is just asking for trouble. And once you start looking at torrents containing dvd & bluray images then 64 bit values become required.


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