uTorrent 3 high CPU usage

[rafi]

Rafi, I'm using a benchmark tool that deliberately does not read any data from disk. The test torrent consists of predictable data that the benchmark tool can generate on the fly, so there should not be any contention over the disk. Also, the machine I'm testing on does have a pretty slow drive, I don't think it can do much better (at random access writes). This is a version of 3.3 with the cache flushing issue fixed as well (we'll release it next week).

Arvid, thanks for posting more details on your test setup. This is helpful in understanding how you test the issue...

I'll send you (or post) more details of my tests later on.

For now it will really help if you can send me a modified version of your load simulator, that can get as input the internal file size, and # of files (instead of the total size, as I have now). This will help in creating more relevant test-torrents (aligned/unaligned).

Here is a link to a test-benchmark tool I'm using to assess my HD random-writes capability/speed:

http://crystalmark.info/?lang=en

1* I'm not sure what is your HD model, but on my very old drive, I get 50M for 512K random writes, and ~10M (as you do) with your simulator local or over LAN. What do you get with it? You might be a bit too "hard" on your HD, with your assumption of it being crappy. Anyways - BT can surly buy you a new one for testing...

2* Do you get the same 10M with an *aligned* torrent/files? A HD can be slow, but the important thing is to *compare* results on it. The ratio should be similar on different disk types.

I'll add/edit this post when I'll complete my tests. You are welcome to send me your test-build with the fixed cache

[rafi]

Here are some of my results (using partfile, coalesce write size of 4M, and a 64M/128M cache):

A previous test with an aligned and unaligned ~4G torrent, 3 internal files (V3.2.1, my faster PC/disk): ~20MB/s vs 40MB/s

Current tests with latest V3.2.2 (on my slower PC/Disk). 3.3 had similar results : ~30MB/s for a single file vs ~12MB/s for unaligned multiple files (seems similar to what Arvid got)

IO Logs from 3.3 and 3.2.2, using DiskMon, that AdamK has asked for:

Single file (or aligned multiple files)) download are: ~2M writes

Un-aligned 10-files torrent: your get a few 64K reads for *every* 2M write. I guess reads are per each piece.

https://docs.google.com/uc?authuser=0&id=0B1fLVXA8Va91VmtSZWprVl8tNVE&export=download

My reference for the *slower* HD random-access benchmark-test:

Another benchmark:

FYI

[arvid]

Rafi, I'm trying to figure out the high CPU usage when downloading torrents with many files. The issue of poorer disk performance when writing to files unaligned is not as surprising, and most likely not a regression.

[rafi]

Those might go hand in hand with each other... More CPU is being utilized to inefficiently and concurrently process I/O of more (usually unaligned) files?...

I see... Did you reproduce it ?

Oh, just curious: what result did you get for that old HD of yours with "my" Cristal random access test-tool ? if it was over 30M - you still have a problem with your/Win I/O handler...

[arvid]

Yeah, I would imagine the reason net-j is seeing this high CPU usage is triggered by unaligned writes, and probably caused by a bad driver.

net-j, is there any chance you could take a few process dumps of uTorrent when it's behaving like this?

Since I can't reproduce it, that would probably give me an understanding of which system call causes the high CPU usage at least.

In order to take a dump, you could use:

http://technet.microsoft.com/en-us/sysinternals/dd996900.aspx

Or you could use process explorer:

http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx

[volverine73]

well, guys, that's just too much.

You have a hundred bug reports about each and every Win7 x64 user having trouble with enormous CPU usage. Two hundred times you responded with something like "the trouble is not with us and our beloved client, go and rattle your own system". Some went and returned with "system's ok, the trouble occurs only when using utorrent". Well, you've been facing it with a kingly silence, not even issuing anything like "we're working on it".

A complete deleting/reinstalling helps for about a week, by the way.

So, I get it, each and every Win7 x64 user may jolly fuck off then.

Well, good to know you guys, I'll just switch to another client and that is my advice to those who was trying to get some help here.

Good luck selling your pay version.

[Switching]

well, guys, that's just too much.

You have a hundred bug reports about each and every Win7 x64 user having trouble with enormous CPU usage. Two hundred times you responded with something like "the trouble is not with us and our beloved client, go and rattle your own system". Some went and returned with "system's ok, the trouble occurs only when using utorrent". Well, you've been facing it with a kingly silence, not even issuing anything like "we're working on it".

A complete deleting/reinstalling helps for about a week, by the way.

So, I get it, each and every Win7 x64 user may jolly fuck off then.

Well, good to know you guys, I'll just switch to another client and that is my advice to those who was trying to get some help here.

Good luck selling your pay version.

Sadly I couldn't agree more. I came here for help with the EXACT same problem, yet can't find any answers. This thread was the closest that it ever got, but fizzled out with a typical "It's not us, it's your computer".

uTorrent is a beautiful little app that I wish I could continue to use. But sadly, there is a massive flaw inside its code which causes massive CPU spikes during downloading. They make my $4000 beast of a computer slow down to a complete halt, can barely even move the mouse.

I've put up with it for until now, but I am finally fed up. It is sad to see this problem go unresolved.

I am switching off your service. Good luck in the future.

[steely74]

It's known issue, try to set net.low_cpu = true in Advanced section of uTorrent's preferences.

thanks! I was having the same issue on windows home server 2011 and this solved it! I had done the cache setting listing in the "best practices" and they helped a tad but not much. this did it! I still see some small spikes up to 10% but I was spiking between 50-70% or more with average around 30-50%.

edit: the issue was happening to me on 2.2.1 as well not just 3.2.3