Kondemand process consumes most of my CPU

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Following is the output from top:

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 3551 mysql     20   0 10.0g  84m 4052 S  9.4  0.1 544:39.87 mysqld
 2311 root      20   0     0    0    0 R  3.1  0.0 184:36.36 kondemand/26
 2296 root      20   0     0    0    0 R  3.0  0.0 183:58.76 kondemand/11
 2297 root      20   0     0    0    0 R  3.0  0.0 183:51.36 kondemand/12
 2299 root      20   0     0    0    0 R  3.0  0.0 183:31.22 kondemand/14
 2304 root      20   0     0    0    0 R  3.0  0.0 183:57.42 kondemand/19
 2310 root      20   0     0    0    0 R  3.0  0.0 182:07.21 kondemand/25
 2312 root      20   0     0    0    0 R  3.0  0.0 184:01.70 kondemand/27
 2314 root      20   0     0    0    0 R  3.0  0.0 182:34.96 kondemand/29
 5255 root      20   0 84432  11m 2800 R  3.0  0.0  58:53.71 cPhulkd - proce
 2286 root      20   0     0    0    0 R  2.9  0.0 179:48.98 kondemand/1
 2298 root      20   0     0    0    0 R  2.9  0.0 183:01.25 kondemand/13
 2300 root      20   0     0    0    0 R  2.9  0.0 183:05.85 kondemand/15
 2302 root      20   0     0    0    0 R  2.9  0.0 181:37.64 kondemand/17
 2305 root      20   0     0    0    0 S  2.9  0.0 182:42.13 kondemand/20
 2313 root      20   0     0    0    0 S  2.9  0.0 183:37.13 kondemand/28
 3264 root      20   0  131m 6236 3712 R  2.9  0.0  13:49.84 cpsrvd (SSL) -
 2287 root      20   0     0    0    0 R  2.8  0.0 155:21.99 kondemand/2
 2289 root      20   0     0    0    0 R  2.8  0.0 181:43.40 kondemand/4
 2290 root      20   0     0    0    0 R  2.8  0.0 180:02.76 kondemand/5
 2293 root      20   0     0    0    0 R  2.8  0.0 179:04.75 kondemand/8
 2294 root      20   0     0    0    0 R  2.8  0.0 182:32.23 kondemand/9
 2295 root      20   0     0    0    0 R  2.8  0.0 184:39.21 kondemand/10
 2306 root      20   0     0    0    0 R  2.8  0.0 182:20.72 kondemand/21
 2307 root      20   0     0    0    0 R  2.8  0.0 182:39.74 kondemand/22
 2309 root      20   0     0    0    0 R  2.8  0.0 179:00.80 kondemand/24
 2315 root      20   0     0    0    0 R  2.8  0.0 182:54.88 kondemand/30
 2965 root      20   0  150m  35m 3464 R  2.8  0.1 177:45.39 httpd
 2291 root      20   0     0    0    0 R  2.7  0.0 180:53.41 kondemand/6
 2292 root      20   0     0    0    0 R  2.7  0.0 179:38.78 kondemand/7
 2303 root      20   0     0    0    0 R  2.7  0.0 184:05.13 kondemand/18
 2316 root      20   0     0    0    0 S  2.7  0.0 182:06.84 kondemand/31

What is it and how do I stop it?

Answer

This is automatic CPU frequency scaling. I suspect that the CPU used by it is actually idled CPU. You can test this by firing up a CPU benchmarking program. You should see the kondemand instances drop to 0% usage. The atop program will display the CPU scaling percentage as well.

Different distributions handle this differently and you didn’t post yours, so I’d take a look at http://www.servernoobs.com/avoiding-cpu-speed-scaling-in-modern-linux-distributions-running-cpu-at-full-speed-tips/?doing_wp_cron=1428304535.5997378826141357421875 as a starting point. This quick script from there will universally turn it off, but you’ll really want to figure out what is done in the startup scripts for your system.

for CPUFREQ in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor;
do [ -f $CPUFREQ ] || continue; echo -n performance > $CPUFREQ; done

It’s probably the case that this is doing nothing worse than saving your power. Unless you regularly have a very bursty workload, you won’t stand to gain much except extra heat by disabling this (unless it’s really broken in your case).

Attribution
Source : Link , Question Author : user4951 , Answer Author : Jeff Ferland

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