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Erratic download speed, something to do with CPU priority.
Posted: June 3rd, 2011, 6:12 pm
by Glottis
Hi, recently my connection was upgraded to 100Mbit and I noticed a really bizarre behavior with SAB. Download speed jumps up and down between 7MB/s to 11.5MB/s, unless I set CPU priority to below medium for SABnzbd.exe. But even then speed isn't the best, I noticed that I get full speed when I have some other application running. I kid you not, once I start other program download speed is 11.5MB/s, when I close it speed becomes erratic and I can do it all day with same results.
Please note that with other NZB clients I get constant max speed, so it's not my ISP shaping speed or anything like that.
Version: 0.6.2 Final
OS: Windows 7 x64
Install-type: Windows Installer
Skin: Plush
Firewall Software: Windows Firewall
Are you using IPV6? no
Is the issue reproducible? yes
Re: Erratic download speed, something to do with CPU priority.
Posted: June 4th, 2011, 4:21 am
by shypike
No idea really.
My system has a very even 11 MBytes/sec over a 100Mbit/sec connection.
Do you measure speed with SABnzbd itself or with another tool?
BTW: do you have an article cache setup in Config->General and how big is it?
Re: Erratic download speed, something to do with CPU priority.
Posted: June 4th, 2011, 4:37 am
by Glottis
I measure speed with SAB, windows task manager and resource monitor. Yes I have cache set as 1G. Tried various sizes.
Re: Erratic download speed, something to do with CPU priority.
Posted: June 4th, 2011, 5:57 am
by shypike
It can happens that SABnzbd just cannot handle the load.
The program is rather CPU-intensive.
How fast is your system? BTW: anything DualCore or better should have no issue,
unless your harddisk is slow.
Can you check what happens if you disable the article cache (set to 0)?
Re: Erratic download speed, something to do with CPU priority.
Posted: June 4th, 2011, 5:56 pm
by Glottis
I have C2D E6750 3.2ghz, 4GB ram. I tried disabling article cache and that didn't change anything.
Re: Erratic download speed, something to do with CPU priority.
Posted: June 5th, 2011, 2:46 am
by shypike
In combination with an internal disk (so not an USB one),
that's perfectly adequate.
One last check.
Set logging to Debug (Status page) and download some time
until you see the speed going up and down.
The open the log (also from the Status page) and search for "delaying" and "undelaying".
If you find those then for some reason the processing of articles
cannot keep up with the downloading.
Re: Erratic download speed, something to do with CPU priority.
Posted: June 5th, 2011, 3:37 am
by judas
Version: 0.6.2
OS: OSX Snow Leopard
Install-type: OSX Installer
Skin (if applicable): Plush
Firewall Software: None
Is the issue reproducible? Yes
So this is my first post here...came by looking for some help.
I have a 4MB connection, but I'm seeing oscillating download speed. I get max speed (around 490Kb/s) and then it goes down, almost to cero, just to climb back up again. I have a screenshot of a graphic showing this, but don't really know if it is ok to post it. It Actually looks like this:
/\_/\_/\_/\_/\_/\_/\_/\_/\_/\_/\_/\
The server is not an issue, as I switched to another entirely different on. and the same thing happened. I wonder if it's related to my hardware (shouldn't be, I'm on a brand new MacBook Pro with 8GB RAM), but if I cap the speed to around 150Kb/s then the download speed is constant at that speed and there are no peaks/valleys.
Any help would be greatly appreciated...
So I have checked what has been said here. I created the cache and played with different values from 70M to 1G, and it made no difference as I'm still seeing the erratic behavior.
Took a look at the log and could't find Delaying or Undelaying text.
Re: Erratic download speed, something to do with CPU priority.
Posted: June 5th, 2011, 10:16 am
by shypike
There are two periodic disk-intensive actions which may delay downloading.
The first is the periodic save of the job's admin to disk.
The second is the assembly of a file from articles when a file is complete.
Depending on the specific system these events may have an effect on the download speed.
For a later release there will be a change that will spread out
disk access over time.
Re: Erratic download speed, something to do with CPU priority.
Posted: June 5th, 2011, 11:58 am
by mrlgm007
I have picked this up as well went back to 0.5.6 every things is fine if you need any info do let me know.
Re: Erratic download speed, something to do with CPU priority.
Posted: June 7th, 2011, 12:56 pm
by judas
@Shypike
thank you for the info...looking forward to next version!
Re: Erratic download speed, something to do with CPU priority.
Posted: June 7th, 2011, 12:59 pm
by shypike
Just for the record.
I do not deny that this uneven download is happening on your systems and that it is new for 0.6.x.
However, so far I have not been able to produce it on any of my systems and its
not generally reported.
I will look into what changed between 0.5.6 and 0.6.x (an awful lot) and what may explain this.
It will take quite while though.
Re: Erratic download speed, something to do with CPU priority.
Posted: June 7th, 2011, 1:31 pm
by shypike
Just a hunch.
How fast is the refresh rate of the queue display in the skin you're using?
Re: Erratic download speed, something to do with CPU priority.
Posted: June 7th, 2011, 3:02 pm
by judas
Mine is 8 seconds at the moment. I'm also using SabConnect++ Chrome extension (15 sec refresh) if that makes any difference?
Re: Erratic download speed, something to do with CPU priority.
Posted: June 7th, 2011, 3:36 pm
by shypike
Slow enough not to be a problem.
Re: Erratic download speed, something to do with CPU priority.
Posted: June 7th, 2011, 7:06 pm
by judas
Ok so I did some tests again and can't see the problem anymore...so maybe it did have something to do with the cache file and it took SAB a while to use it?
Now I have 3 open windows refreshing @ 1 second each, and the download is going on at max speed. I will let you know if I see something else.
Thanks for your help!!