Date: Mon, 28 Jan 2008 03:12:02 +0100 From: Luigi Rizzo <luigi@onelab2.iet.unipi.it> To: "J.R. Oldroyd" <fbsd@opal.com> Cc: Thomas Dickey <dickey@radix.net>, freebsd-stable@freebsd.org, eric@anholt.net Subject: Re: Low CPU Freq responsible for xterm pixel corruption on RELENG_7 Message-ID: <20080128021202.GA59612@onelab2.iet.unipi.it> In-Reply-To: <20080127205400.0a59507d@linwhf.opal.com> References: <20080127205400.0a59507d@linwhf.opal.com>
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On Sun, Jan 27, 2008 at 08:54:00PM -0500, J.R. Oldroyd wrote: > Some weeks ago, I posted on the x11@ list of a problem of pixel corruption > I am seeing in xterm windows. An example of the problem can still be > seen here: > http://opal.com/jr/xterm-corruption.gif > Quick summary: Wide xterm windows (wider than 158 columns, 1440 pixels) > have the problem shown, but only when at least that many columns are on > the screen. That is, moving a wide window so that it is partially off > the screen causes the corruption to cease when less than 158 columns > are displayed. (trimmin thr Cc list) as a matter of fact i have been seeing the same problem also on RELENG_6, on a desktop PC without powerd, and using an Intel chipset with integrated video (i945 chipset) and the I810 driver: X Window System Version 7.2.0 Release Date: 22 January 2007 X Protocol Version 11, Revision 0, Release 7.2 Build Operating System: FreeBSD 6.2-STABLE i386 I seem to remember my laptop (Dell X300, i915 video card) also has similar problems with wide xterms. I believe the problem is in the i810 driver, or some interaction with the system (agpgart) rather than related to powerd and CPU freq. cheers luigi > Further investigation has unearthed that this problem happens only when > the CPU frequency is set to low levels, which was happening because of > powerd. When the CPU frequency is set low, these pixel corruptions happen. > When the CPU freq is raised they do not: everything is normal. > > Disabling powerd and manually adjusting the CPU frequency gives these results: > > # sysctl dev.cpu.0.freq_levels > dev.cpu.0.freq_levels: 3176/-1 2779/-1 2382/-1 1985/-1 1588/-1 1191/-1 794/-1 397/-1 > > CPU freq from 3176 to 1191 causes no problems. > CPU freq at 794 or 397 causes pixel corruptions. > > This problem did not happen on RELENG_6. > > -jr
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