Jump to content

UL overhead while downloading. Problem?


Ecwfrk

Recommended Posts

Overall speeds are fine, so hopefully this the right forum for this ;)

I did a clean OS install on my media server (switched from WHS to WS 2008 R2 x64 Standard) so I upgraded to 2.0.3 (20600) from 1.8 and am experiencing ack upload overhead spiking while downloading.

6s6xiw.gif

The SS is from a test with 4 Ubuntu ISO torrents downloading and one seeding. This is on a completely fresh OS install (fully patched via Windows Update but no tweaks, added roles, or other changes) with default uTorrent settings. The UL speed is a bit low at the point the SS was taken but it did eventually ramp up to full speed (25/3Mbps connection) although the ratio of upload/overhead stayed about the same. I've tried playing with the settings by turning off utp and following each of the suggestions in Rafi's post of tips but with no change in this behavior.

If I stop the downloads and only seed then there's no problem. I only get 20k or so of UL overhead and the actual upload speed to clients goes up to around 300kBps. But if I start even a single download, then the ack upload overhead skyrockets while the amount of bandwidth going to clients plummets.

For the moment I've set uTorrent to apply the rate limit to overhead and have uTorrent set to limit UL speed to 60k (the lowest that gave me full DL speed, although 45-50k of it is overhead) and installed the BT6 client and move finished torrents over to it to seed. If I use uTorrent to seed while downloading I only contribute about 80kBps to the swarms. This way I contribute around 220kBps.

Is there some way to correct this? It doesn't seem to be a very healthy thing if people who are downloading with the same client they seed with lose most of their upload bandwidth to overhead so I'm pretty sure this isn't normal and is probably an issue on my end somewhere.

Link to comment
Share on other sites

Guess I'll have to stick to using separate clients for downloading and uploading then since it's much more efficient then using uTorrent for both at the same time.

It doesn't seem logical that using separate clients to upload and download the same files produces a quarter of the total overhead that using a single client to do both produces. It would seem that the overhead should be the same either way. Weird.

Link to comment
Share on other sites

You don't quite understand. Both clients have overheads and very similar ones at that, the only difference is that utorrent displays it in a seperate slot now. If you find your overheads too high then you need to turn the number of connections down til it is reasonable to you. The more connections up or down the more overhead is used. The speed guide is a good place to start for this.

Also keep in mind that sometimes your hardware can be a restriction as well. Some routers or modems just can't handle that many connections or that frequently, so they end up crashing and or caching stuff which results in slowdowns like yours.

Link to comment
Share on other sites

Even a single TCP connection will have ~3-5% overheads on both download and upload.

Most speed measurements gloss over or don't mention this at all, giving the illusion that these overheads don't exist.

They do, and grow brutally large (even 35+%!) in the worst implementation versions of uTorrent v2.x uTP connections!

Rafi's uTorrent v2.0.X Migration Guide here: http://forum.utorrent.com/viewtopic.php?id=74820

...Can help reduce them, either through disabling uTP (and lose out on an ever-increasing number of peers/seeds) or fixing uTP packet size to max allowed. Do note that latest v2.0.3 should work best with this.

(Seems you've already done most of this...so what was your overhead percentages?)

Link to comment
Share on other sites

When seeding and downloading with uTorrent my UL overhead percentage runs between 75-95% when my DL speed is maxxed out. U: will be around 300k but 240k of it will be overhead.

If I put the downloads in UT portable (which is based on 2.0.2, but shows the overhead) and only seed with uTorrent 2.0.3 then my overall overhead is only 30% or so of my UL connection. The downloading client will be pushing 60-80k (I limit it to 60k UL) with almost all of it being overhead (Up speed column shows peers getting things like 0.3k, if anything at all) while the seeding client pushes 200-220k with only 15-30k overhead. Switching the client roles around produces the same results.

I don't think the number of connections could be a problem since by using separate clients (both with the default of 200 max connections) I've got more connections going than I do with just one client which is verified by my router (WRT54GL with Tomato 1.28 which peaks at about 700 tracked connections with plenty of memory and CPU free).

I did discover that if I limit download speed to 2-3 times my upload speed, the overhead drops dramatically even with the same number of connections. But I'm not nearly advanced enough with networking to know if that actually means anything or is anything that could help figure out why 1 client produces so much more overhead than 2 with all else being as equal as I can possibly make it. My assumption was that it was probably some misconfiguration in my Network or something, but I have no idea what could cause something like that.

Link to comment
Share on other sites

If you download at 1 MegaBYTE/second, that alone can cause ~10-20% overheads on the *UPLOAD* side.

That means about 100-200 KiloBYTES/second upload overhead.

Your screenshot showed downloading at 1.9 MegaBYTES/second, yet you had ~200-300 KiloBYTES/second upload overhead...presumably almost all of it caused by downloading so quickly.

At worst, that would be 15.8% overheads.

At best, 10.5% overheads.

I still don't know your uTorrent settings (especially advanced ones) that may be affecting these conditions.

If you were using a separate bandwidth monitoring program, you'd see these overheads even with other networking using applications...such as downloading from a website using your web browser.

Link to comment
Share on other sites

Yeah. The torrent had only been going for about a minute and the SS was taken in the middle of the day when my cable speed tends to dip.

Here's what I have now if I unlimit the UL on the DL client.

2gsfxjc.gif

If I limit the UL to 60k I get:

i2520h.gif

And if I just seed I get:

14tc4yb.gif

All the settings are the uTorrent defaults (I deleted the settings.dat file to reset them after trying the things in rafi's post as they didn't have any appreciable effect) other than changing the UL rate limit and the queue settings to 5 maximum torrents and 5 maximum downloads.

Link to comment
Share on other sites

try with (per B 1a) :

- BitTorrent->bandwidth management control = disabled. (optional)

- Confirm your actual UL bandwidth, and set UL limit = 370K (~95%)

- bandwidth->apply rate limit to overhead - enabled

This will max you connection w/o chocking it's upload .

You can also -

- set your UL limit to the max seeding speed you like to have (say 200)

- bandwidth->apply rate limit to overhead - disabled

This will limit your seeding to 200K, BUT on the other hand - if you download at the same time - your connection upload is likely to be chocked, thus limiting your download speed when you also - seed.

Link to comment
Share on other sites

Tried that but it didn't help. I think I've banged up against some kind of freakish bug (not necessarily with uTorrent).

I reinstalled 1.8 and while it doesn't explicitly show overhead, I don't believe it adds overhead to the speeds shown in speed columns in the main windows and with a bit of addition that showed me downloading at about 3.0Mb/s and uploading at around 200k.

So it seemed to be an issue with 2.0.x. But to make sure, I installed WHS and Win 7 Ultimate on the server (using spare drives) and results in WHS with 2.0.x on WHS are on par with what I get with 1.8 on WS 2008R2 (3.0Mb/s downloads, ~200k uploads with 60-100k UL overhead) while results with 2.0.x on Win 7 were not quite as good as under WHS (20-40k more UL overhead), they were nowhere near as bad as what I get under 2008R2.

So it doesn't seem like there's anything wrong with uT 2.0.x unless it's installed on WS 2k8R2. I'm going to try it on some different hardware when I get the chance to try and discern if it's WS2k8 or if it's WS2k8 + my hardware causing the problem but it'll be a few days before I can do that.

Link to comment
Share on other sites

unless it's installed on WS 2k8R2

Interesting... Maybe you can compare net.disable_ipv6 & net.max_halfopen between the OSes.

I'm not sure uT knows to recognize the OSes to set them as intended. Try set them manually to the same value on the other OS.

Link to comment
Share on other sites

I did that last night on 20600 and it didn't seem to make any difference.

However the new 20664 build seems to have solved the problem. I'm downloading at 3MB/s right now and uploading at 230k with only ~120k of overhead. :D

Link to comment
Share on other sites

I tried it enabled and disabled with the previous build and there wasn't any change when I did.

Edit: I just enabled it (set net.disable_ipv6 to false) on 20664 and it also didn't cause any change. Still only ~120k overhead.

Edit 2: Reinstalled 20600 over top of 20664 (didn't delete the existing settings.dat, ipv6 is disabled) and overhead went right back up. Switched back and overhead is down again.

Link to comment
Share on other sites

Well, thats something to work from now I guess, there is a beta that does the job, just gotta figure out what got changed after and what went wrong with it.

What do you mean by ugly, its a new icon design yes, but it was about time. Did it switch back after 664?

Link to comment
Share on other sites

If you like it, cool. I don't. You liking it doesn't mean I have to "get used to it". There's no guarantee they will actually adopt it in all clients. And if they do, there's always skinning it or using a different client.

The important thing is that the client I'm using works now. If you want to discuss the merits of a change in the UI, we can do that in the UI Design forum. :D

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...