Posts Tagged ‘CPU limit’

SABnzbd and high CPU usage on weak CPUs

Sunday, July 21st, 2013

SABnzbd is a nice tool. I just replaced my previous nzbget with it, due to its better handling of the obfuscated names in usenet groups. However, on an Atom CPU, the max download speeds did not go over ~5MB/s on a 100Mb/s link. This is rather sad, because nzbget did get the whole ~11MB/s speeds.
The source of this slowness is the handling of the SSL within python (or SABnzbd, to be exact) which cannot exceed a single core. A workaround for this problem was using stunnel with the SABnzbd, as described here. Because stunnel uses multiple cores, handling of the connections can exceed the rather weak CPU limit into other cores. Following this procedure, I was able to reach 11-12MB/s speeds.

Notice a little correction: The bottom string: connect, has to have the equal sign, like this:

connect =

RHEL4 can see only 8 cores out of 16 cores server

Wednesday, May 21st, 2008

I have encountered it on several cases. RedHat Linux ES, by default, uses smp kernel which is limited to eight cores, or two sockets. You find out that your multi-socket hardware, with its 16 (or more…) cores show you only the first eight, both by the simple method of running ‘top‘ and then pressing on ‘1‘, or by running ‘cat /proc/cpuinfo‘.

A simple solution to the problem is to change grub so it loads the largesmp kernel at boot time, and reboot. You will get all your cores.

This is not required, for some reason, on AS server.