# \[FIXED\] CPU usage VERY HIGH on a single core **URL:** \ **Category:** Asterisk Support\ **Created:** [April 8, 2015, 8:17am UTC](https://community.asterisk.org/t/fixed-cpu-usage-very-high-on-a-single-core/48613 "2015-04-08T08:17:13Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![tommer](https://avatars.discourse-cdn.com/v4/letter/t/e9c0ed/32.png) [@tommer](https://community.asterisk.org/u/tommer)\ **Post date:** [April 8, 2015, 8:17am UTC](https://community.asterisk.org/t/fixed-cpu-usage-very-high-on-a-single-core/48613/1 "2015-04-08T08:17:13Z")
I have an Asterisk 11 server (AsteriskNOW installed without FreePBX, based on CentOS 6) running as a VM with 12 cores. The server has been updated with yum update to have the latest Asterisk and CentOS 6.6 updates. It is currently running around 1000 simultaneous SIP-channels that are evenly spread on 200 different ConfBridge conferences. 60% of them use G.711 (SIP-trunks from ordinary phones) and 40% of them G.722 (SIP-phones). My problem is that using htop, top or mpstat i see a single CPU core being very loaded, but not the others, like if there was a single thread using a lot of CPU. But if i change htop or top to look at threads instead of processes, then there is no single thread using more than a few % CPU. Another strange thing is that Load Average shows very low values. See the screenshot of htop below (PID: 2270 is the complete Asterisk process, and the asterisk PID’s below it are all the threads it consists of) ![](https://dl.dropboxusercontent.com/u/72146645/AsteriskCPUload2.jpg) I am wondering: [ul]Is the info about one CPU core being very loaded correct? What will happen when it reaches 100%?[/ul] [ul]If the info is correct, why does Asterisk/CentOS not move some of the load to other CPU’s so the load is even, when you can clearly see that there is not a single thread using alot of CPU?[/ul] [ul]Why is Load Average so low when you can clearly see that the Asterisk process uses 432% CPU? - Load Average should show something close to 4.0-4.5[/ul] To test if Load Average was working correctly i have tried to create a bash loop script to put 100% CPU load on one core, and then run the script multible times simultanously. If i run the script twice to put 100% load on 2 CPU cores then Load Average shows 2.0 correctly. Can anybody explain this, or give me some insights? ---
**Author:** ![system](https://global.discourse-cdn.com/asterisk/original/2X/4/475d0c889911cfb84ac4881ad6df8b523e3f9105.png) [@system](https://community.asterisk.org/u/system)\ **Post date:** [April 8, 2015, 8:50pm UTC](https://community.asterisk.org/t/fixed-cpu-usage-very-high-on-a-single-core/48613/2 "2015-04-08T20:50:09Z")
A similar problem after the upgrade to asterisk11-11.17.0 FreeBSD pbx 10.1-RELEASE-p9 FreeBSD 10.1-RELEASE-p9 #0: Tue Apr 7 01:09:46 UTC 2015 [root@amd64-builder.daemonology.net](mailto:root@amd64-builder.daemonology.net):/usr/obj/usr/src/sys/GENERIC amd64 [code]last pid: 34196; load averages: 1.10, 1.15, 1.08 up 0+02:02:03 23:47:39 25 processes: 2 running, 23 sleeping CPU: 10.7% user, 0.0% nice, 41.4% system, 0.0% interrupt, 47.9% idle Mem: 151M Active, 451M Inact, 162M Wired, 202M Buf, 1200M Free Swap: 4096M Total, 4096M Free PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND 33945 asterisk 40 103 0 585M 58908K CPU0 0 40:58 100.00% asterisk[/code] ---
**Author:** ![david55](https://avatars.discourse-cdn.com/v4/letter/d/e19adc/32.png) [@david55](https://community.asterisk.org/u/david55)\ **Post date:** [April 8, 2015, 8:51pm UTC](https://community.asterisk.org/t/fixed-cpu-usage-very-high-on-a-single-core/48613/3 "2015-04-08T20:51:13Z")
Scheduling of work to CPUs is done by the OS, not by Asterisk. ---
**Author:** ![tommer](https://avatars.discourse-cdn.com/v4/letter/t/e9c0ed/32.png) [@tommer](https://community.asterisk.org/u/tommer)\ **Post date:** [April 9, 2015, 7:13am UTC](https://community.asterisk.org/t/fixed-cpu-usage-very-high-on-a-single-core/48613/4 "2015-04-09T07:13:32Z")
It seems to be related to the NIC only using CPU0. When looking in /proc/interrupts its clear that the IRQ that eth0 uses only runs on CPU0 even though irqbalancer is running. ---
**Author:** ![tommer](https://avatars.discourse-cdn.com/v4/letter/t/e9c0ed/32.png) [@tommer](https://community.asterisk.org/u/tommer)\ **Post date:** [April 15, 2015, 11:57am UTC](https://community.asterisk.org/t/fixed-cpu-usage-very-high-on-a-single-core/48613/5 "2015-04-15T11:57:51Z")
After switching from E1000 vNIC (which only uses one CPU), to VMXNET3 vNIC the load from the NIC is now spread out over 8 CPU cores.