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Large percentage of wasted data (1.4 b406)


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Hi, I've been using µTorrent since version 1.1...

Up until 1.3, the average wasted data on every torrent varies between 1-10%...

Then I tried 1.4 and suddenly the wasted data averaged at about 25-40%...

I noticed this because EVERY torrent (about 8 torrents) resulted the same percentage of wasted data...

Then I downloaded 1.4 build 406, same result...

So I tried testing it with the same torrent...

I tried downloading same file (50MB) which has about 100 seeds...

1.3 "creates" 2MB of wasted data...

1.4 b406 suprisingly hits 14MB...

I'm using the same settings for both test...

I have a 128/64 connection, so I limited the upload to 5 KB/s...

And a maximum connection of 50 per torrent...

I thought that 1.4 reduces wasted data... :(

With my connection, a 25-40% wasted data is HUGE ! :D

I'm revert to 1.3 and the wasted data is much much smaller (<10%)...

What triggers this "bug"..?

Thanx in advance ! :D

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Hi, i had the exact same experience when i went from 1.3 to 1.4

-Lots of wasted datas, in extreme cases 40 to 50 % of the filesize.I had almost no wasted datas with 1.3 (build 364)

My connection speed is 128/64 exactly like you, maybe this is the key...

I went back to 1.3 and no more wasted bits/bandwith.

Hope it can be fixed, because otherwise utorrent is the best piece of code among BT clients IMO.

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My guess is you're spreading your upload very thin with too many upload slots. Then, ironically, you ARE getting download bandwidth back from the people you're uploading to...but since you're uploading very slowly PER person the return is equally slow. Since it is very slow for each person, µTorrent might be downloading from 10+ people to fill up a single chunk...and get LOTS of overlaps as some of those uploading to you speed up and slow down. Those overlaps are wasted data.


What is your upload slots set to, and how many torrents are you trying to download at once?

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Thanks for the quick answers.

For the ul speed/ul slots ratio, it certainly makes sense, but i'm well aware of that since with a 128k connection i can't do whatever i want.What i do is leeching torrents that have little peers, (between 1 and 15 max) and avoid big crowded torrents that just got announced.But once i'm finished dl it, i keep it seeding for a long time.

Also, I always keep an eye on the dl/ul speeds in UT to never reach the max capacity of the line, but i uncap everything (except 5 ul slots/torrents).This way things go slowly never reaching the line limits and there's room for everything.

It gave me excellent results with UT 1.3 with very little wasted datas (between 0% to 5 %).That's why i loved this soft, was perfect for my conditions of use.

Firon: Yes definitely.On a 15 peers torrent i'm getting 5% of wasted datas with UT 1.3 (build 364) and 44% with UT 1.4.1 beta (build 406).

I'm doing a test to compare both versions with same settings.Can it help if i post it here ?

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The upload slot...

Never thought of that... :D

I set my upload slot to 2, and maximum number of active torrent of 4 and maximum download of 2...

Firon, since this problem is introduced with µTorrent 1.4, maybe you could tell us what caused this problem..? :D

Just for our knowledge...

Thanx !

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Also, I always keep an eye on the dl/ul speeds in UT to never reach the max capacity of the line, but i uncap everything (except 5 ul slots/torrents).

5 upload slots per torrent is near the upper limit of what will work well for 1 torrent. If 1 torrent is seeding and another downloading it is definitely too many.

I presume your upload speed is between 9 and 12 KB/sec, as you said you keep dl/ul values conservative. With 5 upload slots, the best average speed you can hope to give to someone is 1.8-2.4 KB/sec. Many BitTorrent clients may return the favor with some of their own upload bandwidth, but often only about 25-80% that amount since it's a little on the low side. They probably have faster uploaders to tit-for-tat with too, which receive most of their upload bandwidth. So you're getting back about 0.5-2 KB/sec from 5 peers and whatever you can leech from seeds. If all 5 peers are uploading parts of the same chunk to you and all going 2 KB/sec each, that's only 10 KB/sec total. For a chunksize of 1 MB, that will take 103 seconds and have at least 4 points of overlap where 1 peer's range hits another peer's range.

Older versions of µTorrent probably typically requested different chunks from each peer, so overlap wasn't as big an issue...however because each chunk took longer to get, there's a bigger time delay before you get any new chunks to share.

If you limited upload slots to only 2 or 3 and checked "use more upload slots if upload speed <90% max", then your wasted space on torrents would probably be less than half and your download speeds would probably increase slightly.

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Switeck: I never get such an upload speed on the torrents i'm leeching, far from it.And there's no way to have more than 8 or 9 kb/s with a 128/64 line because it's the theorical maximum.

Look,yesterday i did a little test to compare both versions.I followed your advice.Only one torrent was running with about 15 peers and 1 seed.Only 2 upload slots.Dl speed was about 5 kB/s, and ul around 3 kB/s.Nothing else running.After an hour i had near 50% wasted datas in 1.4.1 beta (also with 1.4).

Same test with 1.3, exact same settings, same time running and i get around 5 % wasted datas.

So it's not about upload slots, nor bandwith limitation because i never reached more than 30% of the line capacity in DL and 35 % in UL.

For me something has changed in the code that doesn't fit with low bandwith, or something else, i don't know.

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Sorry, I misread your "128 connection" to mean 128 kilobits/sec upload.

Strange that your download and upload results were so low, unless you limited upload and download to that amount. From personal experience, if my connection was capable of it, if I set upload speed to something µTorrent ran very close to that value. Download speed on the other hand...well, I don't expect to get more than about double upload speed except in extreme circumstances.

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