Tuning the scheduler? Desktop with a CPU-intensive task becomes rapidly unusable.

Andriy Gapon avg at icyb.net.ua
Thu Sep 2 10:28:12 UTC 2010

on 02/09/2010 12:08 jan.grant at bristol.ac.uk said the following:
> On Wed, 1 Sep 2010, Ivan Voras wrote:
>> On 09/01/10 15:08, jan.grant at bristol.ac.uk wrote:
>>> I'm running -STABLE with a kde-derived desktop. This setup (which is
>>> pretty standard) is providing abysmal interactive performance on an
>>> eight-core machine whenever I try to do anything CPU-intensive (such as
>>> building a port).
>>> Basically, trying to build anything from ports rapidly renders everything
>>> else so "non-interactive" in the eyes of the scheduler that, for instance,
>>> switching between virtual desktops (I have six of them in reasonably
>>> frequent use) takes about a minute of painful waiting on redraws to
>>> complete.
>> Are you sure this is about the scheduler or maybe bad X11 drivers?
> Not 100%, but mostly convinced; I've just started looking at this. It's my 
> first stab at what might be going on. X11 performance is usually pretty 
> snappy. There's no paging pressure at all.

>From my experience:
1. system with Athlon II X2 250 CPU and onboard AMD graphics - no issues with
interaction between buildworld and GUI with all KDE4 effects enabled (OpenGL).
2. system with comparable Core2 Duo CPU and onboard Intel graphics (G33) -
enabling OpenGL desktop effects in KDE4 leads to the consequences like what you
describe.  With all GUI bells and whistles disabled the system behaves quite
like the AMD system.

Andriy Gapon

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