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

[Andriy Gapon]

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