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High Virtual Memory

Posted: June 24th, 2012, 1:25 pm
by fungusfeet
I'm running SAB and Sickbeard together on a NAS (Dlink DNS320), these are the only things installed. I have a debian installation on a usb stick running both apps via python downloading direct to the hard drive. Everything is fully up to date, using version 0.7.0.

My latest attempt to install was yesterday and everything was working very quickly, I added all my shows on Sick Beard and both web gui's were still snappy. Gradually over the last 24 hours the box has got slower and slower, I can't play any music through itunes now as the library is located on the nas and it takes about 2 minutes to connect via ssh.

Running a top command gives this...

Image

Both apps are using a huge amount of virtual memory and very little CPU, so I'm guessing the VM usage is what is slowing everything down.

Anything I can do to limit the VM usage, maybe automatically flush the VM every so often? I have no idea, still new to linux.

Re: High Virtual Memory

Posted: June 24th, 2012, 2:42 pm
by shypike
How much memory does your system have?
Did you set an Article cache in Config->General?

Re: High Virtual Memory

Posted: June 24th, 2012, 3:11 pm
by sander
shypike wrote:How much memory does your system have?
See the upper lines of the screendump: 128 MB RAM, plus 524 MB swap.

@OP: 128MB RAM is very, very little RAM for SABnzbd. As you have swap (on your USB stick, so slow), your OS will start swapping, ... which will make the system very slow ... which matches your experience.

EDIT:

PS: your load average (upper right corner) is 5 and higher. That means an average of 5 processes *waiting* to be handled by the CPU. That's bad. My rule of thumb: load average should be below 1. The more it is above 1, the more your system is overloaded. A number 5 means a horribly slow system.

You could consider using NZBget instead of SABnzbd.

Re: High Virtual Memory

Posted: June 24th, 2012, 4:44 pm
by fungusfeet
I've set an article cache of "1M" as I wasn't really sure how to turn it off.

I've set logging in sickbeard to a minimum of errors only and it seems to be running better but I'll see how it 's going after another 24 hours. (downloads occasionally slow down into the 10's of KB/s)

I don't really understand the CPU load average of 5 thing...the CPU is an 800mhz arm processor. Does the 5 just mean the CPU isn't fast enough or there's too many processes?

Re: High Virtual Memory

Posted: June 24th, 2012, 4:54 pm
by sander
fungusfeet wrote: I don't really understand the CPU load average of 5 thing...the CPU is an 800mhz arm processor. Does the 5 just mean the CPU isn't fast enough or there's too many processes?
There are too many processes waiting to be handled by the CPU. In the ideal case the CPU is waiting for processes to be handled (meaning a process has zero wait time, and thus it's fast). In a bad situation, the processes are waiting to be handled by the CPU (causing slowness).

It could be your CPU, and/or too many / heavy processess, and/or the slow swap device. Check what happens to the load when you kill SABnzbd and CP. Does it get below 1?

Re: High Virtual Memory

Posted: June 24th, 2012, 5:11 pm
by fungusfeet
I guess I was downloading at the time of that screenshot, this is with nothing downloading but sab & sb running.

Image

And this is downloading at 1.3MB/s

Image

downloading has really slowed up everything and it's struggling to keep a consistent speed, in previous attempts downloading hasn't really made much of an impact on system performance.

(Speed is dropping down to 40 KB/s...something's definitely up with it this time.)

I don't get why everything is fine when I first install it then it just slows to a standstill. The system can obviously handle it if it works for a while.