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I have Ubuntu 14.04 LTS x64 running on my PC: AMD Phenom 9650, 4GB DDR2 RAM, 250 GB HDD.

When I start 4 instances of a program that requires full CPU power, the whole Ubuntu is hardly usable any more.

I tried assigning lower priorities to the processes, by using Ubuntu's pre-installed system monitor - does not help, still Ubuntu reacts to mouse- or keyboard input like chewing gum.

What can help to use 100% CPU power and keep the system working 'smoothly'?

J. Doe Flow
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  • FWIW: I had a related, though not identical issue. I managed to solve it completely by switching to the noop scheduler. There are some critical issues with current (more complex) schedulers in Linux failing to favor interactive processes. See also:https://askubuntu.com/questions/765692/scheduler-how-to-tune-cfq-to-favor-interactive-processes/770958 – arielf Jul 25 '16 at 20:44

1 Answers1

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You should invoke your CPU hogs with the nice command. man nice says: 

NAME
       nice - invoke a utility with an altered nice value

SYNOPSIS
       nice [-n increment] utility [argument...]

DESCRIPTION
       The nice utility shall invoke a utility, requesting that it be run with
       a  different  nice  value  (see  the   Base   Definitions   volume   of
       IEEE Std 1003.1-2001,  Section  3.239, Nice Value).

This is the POSIX way to adjust CPU priorities. Now, you have to worry about memory contention, swapping, etc.

waltinator
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  • Thank you for your answer. Unfortunately 'nice' did not really help. I ran 4 instances of the same program in 4 terminals, each via command 'nice -n 10 ./program' - when browsing in Firefox besides, scrolling webpages still is very jumpy and 'hangs' sometimes :( I suppose this could be a design problem caused by the way Ubuntu's scheduler is programmed - my Windows Vista is also jumpy but works better at 100% CPU load, honestly. – J. Doe Flow Sep 08 '15 at 18:37
  • You have now entered the mystical and confusing realm of "linux performance analysis". Search on that. Start by running "System Monitor" – waltinator Sep 08 '15 at 21:04