Date: Thu, 2 Sep 2010 11:46:04 +0100 (BST) From: jan.grant@bristol.ac.uk To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-stable@freebsd.org, Ivan Voras <ivoras@freebsd.org> Subject: Re: Tuning the scheduler? Desktop with a CPU-intensive task becomes rapidly unusable. Message-ID: <alpine.BSF.2.00.1009021133330.5858@tribble.ilrt.bris.ac.uk> In-Reply-To: <4C7F7C0F.8080004@icyb.net.ua> References: <alpine.BSF.2.00.1009011357050.5858@tribble.ilrt.bris.ac.uk> <i5lr29$9ei$1@dough.gmane.org> <alpine.BSF.2.00.1009021000110.50312@tribble.ilrt.bris.ac.uk> <4C7F7C0F.8080004@icyb.net.ua>
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On Thu, 2 Sep 2010, Andriy Gapon wrote: > on 02/09/2010 12:08 jan.grant@bristol.ac.uk said the following: > > On Wed, 1 Sep 2010, Ivan Voras wrote: > > > >> On 09/01/10 15:08, jan.grant@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. All desktop effects are disabled. The graphics are from an nVidia GeForce 8500 GT (G86) with the X.org driver. (It's not _just_ desktop behaviour that's affected, though: the box runs a number of small headless [interactive] server processes which also appear to get rapidly starved of CPU time.) The behaviour isn't visible with the 4bsd scheduler; "stuff" generally remains snappy and responsive. I'll keep poking around and see if I can get to the bottom of it. -- jan grant, ISYS, University of Bristol. http://www.bris.ac.uk/ Tel +44 (0)117 3317661 http://ioctl.org/jan/ Rereleasing dolphins into the wild since 1998.
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