Still too much CPU consumption - especially when using Kontact.

[Guus]

On 22/04/12 18:11, Bas Roufs - message in English wrote:
>
> Hello everybody
>
> Today, I have been tweeking with a view to limiting the use of CPU by 
> the system Kubuntu 11.10. I have followed most of the advises at the 
> tutorial "How to make Kubuntu (KDE) blazing fast and optimise it for 
> performance".
>
> See: http://bit.ly/tRJzap
>
> This has helped to effectively deal with the worst CPU problems I have 
> experienced recently. However, the consumption of CPU is still 60 up 
> to and including 100% in certain situations - notably when syncing 
> IMAP-folders in KMAIL/ Kontact. As a matter of consequence, it is very 
> difficult to multitask with one or a few other packages, when doing 
> so. At one of the two laptops I am working with, I even need to use 
> some workarounds via the system activity monitor to get Kontact 
> started at all: "killing" one or two processes, while prioritising 
> others.
>
> Be so so kind to provide me with feedback and ideas to handle this 
> problem.
>
> Respectfully yours,
>
> Bas Roufs.
>
Hi bas,

This sounds very annoying. The system being non-responsive effective 
prevents you from working properly.
Did you try isolating the culprit in a cgroup? That way you can maximize 
the processor power it is allowed to use.
I didnt try it yet, but I plan to if I get problems like this.

Below a summary of what I read in the Dutch "Linux magazine" 2012-02. 
Hope it helps.
Remember to change names to your own situation.

mkdir -p /cgroup/cpu
mount -t cgroup -o cpu none /cgroup/cpu
(check with ls -l /cgroup/cpu it works, you should get something like:

root at mahatma:/# mkdir -p /cgroup/cpu
root at mahatma:/# mount -t cgroup -o cpu none /cgroup/cpu
root at mahatma:/# ls -l /cgroup/cpu
total 0
-rw-r--r-- 1 root root 0 2012-04-23 05:24 cgroup.clone_children
--w--w--w- 1 root root 0 2012-04-23 05:24 cgroup.event_control
-rw-r--r-- 1 root root 0 2012-04-23 05:24 cgroup.procs
-rw-r--r-- 1 root root 0 2012-04-23 05:24 cpu.rt_period_us
-rw-r--r-- 1 root root 0 2012-04-23 05:24 cpu.rt_runtime_us
-rw-r--r-- 1 root root 0 2012-04-23 05:24 cpu.shares
-rw-r--r-- 1 root root 0 2012-04-23 05:24 notify_on_release
-rw-r--r-- 1 root root 0 2012-04-23 05:24 release_agent
-rw-r--r-- 1 root root 0 2012-04-23 05:24 tasks
root at mahatma:/# cat /cgroup/cpu/cpu.shares
1024

The 1024 is equal to 100% of your CPU. All processes in the file "tasks" 
share these 1024 cycles.

Now suppose you have a certain set of processes (or only one) that hog 
the cpu.
Then you create a new directory and direct these processes to that 
directory.
Only this time you maximize the number of cycles it is allowed to use.

First you create a subdirectory under CPU, this doubles the number of 
cycles to 2x1024. Then you limit the number of cycles by overwriting the 
cpu.shares file with a smaller number. Then you copy the processes that 
you want limited to the tasks file in the subdirectory.

 From that time on, these processes should be limited in CPU use to the 
shares you specified. I copied from my machine, but dont have any 
processes to put in tasks:

root at mahatma:/cgroup/cpu# mkdir vreters
root at mahatma:/cgroup/cpu# ls -l vreters/
total 0
-rw-r--r-- 1 root root 0 2012-04-23 09:27 cgroup.clone_children
--w--w--w- 1 root root 0 2012-04-23 09:27 cgroup.event_control
-rw-r--r-- 1 root root 0 2012-04-23 09:27 cgroup.procs
-rw-r--r-- 1 root root 0 2012-04-23 09:27 cpu.rt_period_us
-rw-r--r-- 1 root root 0 2012-04-23 09:27 cpu.rt_runtime_us
-rw-r--r-- 1 root root 0 2012-04-23 09:27 cpu.shares
-rw-r--r-- 1 root root 0 2012-04-23 09:27 notify_on_release
-rw-r--r-- 1 root root 0 2012-04-23 09:27 tasks
root at mahatma:/cgroup/cpu# cd vreters
root at mahatma:/cgroup/cpu/vreters# cat cpu.shares
1024
root at mahatma:/cgroup/cpu/vreters# echo 256 > cpu.shares

Now you have 1024 + 256 cycles: about 20% for all processes in this 
tasks file. The tasks file is currently empty.
All you have to do is copy 199001 to tasks (if that is the process that 
is hogging the CPU): echo 19901 > tasks

 From then on, you should have a more responsive system. You can find 
out what is wrong with the process later.

I really hope this helps.

-- 
Kind regards, Guus Bonnema.
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