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wewt

Random speed drops

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Well I have now tested the 2.0 on the same torrent with the same number of peers several times and each time. With default utp and tcp enabled. I can reach only about 2.5MB/s UL speed. Yet each time with only TCP enabled. I can reach about 5MB/s on the same torrent with the same number of 26 peers.

Tested now several times so TCP still seems to be more reliable for uploading.

bt.trans_disposition in advanced.

5 is TCP only

10 is utp only

15 is both.

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Ok, we'll look in to that.

Just to be clear though, the bt.tcp_rate_control speed difference is -not- related to the Windows disk cache options which cause the "Random speed drops" this thread is about.

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Hy!

I've also had this problem for a few months, ever since I installed Vista and now Windows 7.

Exact symptoms where utorrent tries to write to disk, but no disk operations are actually performed.

In my experience, utorrent only hangs once (usually when I start the torrent) and once it resumes disk operations everything goes back to normal without other hiccups.

This only happens with big torrent and >5MB/s download speeds. I think it's dependent on a torrent's piece size or block size, but I can't fully confirm this because of the bug's inconsistent behavior.

Tested with a single torrent downloading. Windows caching of disk writes is disabled. utorrent cache manually set to 256MB or 512MB, but on a normal run it never gets higher than 32MB of usage and it only masks the bug until the cache fills.

SATA drive with AHCI, no RAID, no SMART errors or drive failures and utorrent is the only program I had this problem with. When switching from Vista to Windows7 I also switched hard drive, but the problem persisted, so I don't think it's a drive problem.

My Asus P5E3 deluxe motherboard has an Intel ICH9R controller.

Hope this helps!

Edit: windows firewall disabled, no antivirus, no "active" defragmenter, or any other program that hooks disk IOs. x64 operating system. utorrent version 1.8.5

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Can you post details of the event in Process Monitor which takes that time? It of course will not appear until it completes - so stop the monitor after uT picks up again and scroll back to find it.

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Sorry, I tried and failed. This bug only appears to me only once in a while and can't predict when it will happen again.

In my particular case, I found that it mostly happens when utorrent is closed and I run a .torrent file to start downloading it immediately.

When I'll have time I'll try to force the bug to appear and be ready with the process monitor open.

It is not a serious problem, but it is a strange one.

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Hello there,

ive had this same problem with upload dropping now just when i updated from WinXP 32 -> Win7 64bit

Before i was baffled why my uploadspeed dropped randomly to zero, and then a couple of seconds after picked up again to drop again and again. Just to clarify, downloads havent been a problem since:

diskio.no_zero true

diskio.sparse_files false

But when i uploaded this one torrent i happened to look at it just when my upload dropped the first time in that torrent.

Overview of the incident:

http://i45.tinypic.com/w4niq.png

zoom:

http://i47.tinypic.com/jrw8ar.png

removed the limiter again just for kicks:

http://i50.tinypic.com/30t0zv9.png

re-enabled the limiter:

http://i50.tinypic.com/nufds.png

weird? not? uTP only? i didnt have time to test if disabling the disk cache removed the drops even with uncapped upload. I have 6GB ram so i use

manual 600MB cache,

disabled windows read cache,

disabled remove old blocks,

disabled reduce mem usage

the cache just sits at 600MB usually always. (read or write if dling)

I have a 100Mbit ethernet connection to the internet, but my ISP limits the upload to something 10400kbit/s or 1,27MB/s. I have reached this on average with a single TCP connection to a friends computer nearby.

uTorrent shows usually 1,2MB/s and is happy with 1285kB/s upload limit as you can see. Going higher than that with only TCP connections makes it zig-zag, but the average is probably the same or insignificantly higher.

EDIT: On a side note if i upload a small file ~5MB, the process takes a second or less and shows as high as 6MB/s transfer rates to good connections. Seems like the ISP limiter takes some time to kick in. The link is 100Mbit after all. Thats why there is a high peak after i removed the upload limit on the 3rd screenshot.

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I've had the some problem for ages (pre 2.0) with upload speed dropping to zero a few times per hour. Same error happened on my old P4 server (ran WinXP and Win7 at the end) and my new Atom server (Win7). I've 100/100 Mbps.

I tried following Switeck's advice, that didn't help. I then did what zyrobs wrote and disabled "caching of disk reads". It seemed to help but that led to Win7 cache filling up all my 4 GB RAM. I know cache works differently than in WinXP, but with utorrent cache off Win7 seems to "reserve" all RAM for utorrent caching, only leaving a few hundred MB for the rest of the system.

But zyrobs's settings didn't actually help either, I just managed to miss it because of utorrent's 5 min stats. This loss in upload won't show up on my 5 min stats, if it shows up at all it's just a small dip (almost half between zero and normal upload speed) never touching zero. So the only way to spot this error is to keep checking the 30 second stat.

Anyway, I'm tired of this and gonna try out rtorrent with rutorrent. I don't really have any reason anymore to run Windows on the server.

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Please allow me to bump this.

I have tested using a RAMDrive, with the tools linked in the above (the My Digital Life link). I'm using a 700mb torrent with a lot of leechers, on a 1gb ramdrive.

When only running the torrent pointing to the RAMDrive, the stalls do not happen. But this may be cause speeds are not high enough.

When running every one of my torrents normally, the stalls happen as usual. What's strange is that the other torrents don't contribute much to my upload speed, not enough to normally cause the stalls by themselves (1-2 hundred kbytes/sec for HDD torrents, 1.5mbyte/sec for the RAMDrive one. Also, when the stalls happen, even the torrent on the RAMDrive gets stalled!

The test hardware is the same as before, except that it now has 4gb ram.

I've also tried removing every additional read caching option in Windows (such as the extended buffer under device properties), but they didn't have any effect either. Tried changing AAM/APM values, no go there either.

The only thing I haven't tried so far was switching the motherboard SATAII controller back to legacy IDE mode.

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hmmm im have the same problem as u but my download suddenly will drop from a high speed to verly low or even zero iv tried alot of different things. what should i change in my disk cache configuration u think ? THANKS

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zyrobs, I asked the uTorrent devs about your problem and got this reply:

[01:48] <alus> Switeck: the uT disk thread is just one thread

[01:48] <alus> Switeck: so anything that stalls it stalls all future diskio

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Okay, I think I can say that I'm extremely annoyed. I switched back all the SATA ports on my motherboard from AHCI to Legacy IDE mode and the stalls don't happen now, infact I don't even get any measurable speed impact even if I put extreme load on the HDD I'm seeding from.

I'll try updating drivers. As far as I understand, AHCI should be better, isn't it?

EDIT: My motherboard has a 82801IB ICH9 Base controller, which apparently does not support AHCI to begin with. I wonder why there is an option in the BIOS to enable this function, when it does not work.

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Bumping this for one final time. The problem solved itself when I finally tracked down a working ICH9 Base AHCI controller driver. Utorrent speeds are now rock stable, and the rest of my computer is much faster too.

To any other high-speed users experiencing speed drops to zero, make sure your ide/sata drivers are properly set up.

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