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-   -   Xorg high CPU usage on scrolling and moving windows (http://www.nvnews.net/vbulletin/showthread.php?t=154661)

MadCatX 09-01-10 08:10 AM

Xorg high CPU usage on scrolling and moving windows
 
2 Attachment(s)
Hello,

For the last few days I've been experiencing quite odd behavior regarding Xorg. Xorg seems to use about 70 % of CPU when I scroll through a document in Kate, webpage in Opera etc. In KSysGuard I can see that both of my CPU cores have over 50% load. When the system is idling, Xorg uses from 1 % to 8 % CPU. Moving windows exhibits the same behavior.
This happens regardless to compositing or window manager. I tried KWin and OpenBox in KDE 4.5, I also tried running just plain X with TWM, but the problem remains. The problem initially appeared with Xorg-server 1.8.1 and 256.44 drivers, update to 256.53 and Xorg-server 1.9 didn't change a thing. I also tried downgrading to 2.6.34.6 kernel to no avail.
I'm currently running Xorg-server 1.8.1, 256.53 drivers and 2.6.35.4 kernel with BFS and BFQ.

There is another rather strange issue with MPlayer and VDPAU which might not be related. If I play a clip encoded in H264 using VDPAU and HW accel, X uses about 30% CPU (sometimes as much as 50%) when compositing is enabled. Disabling compositing makes X to drop below 5%. MPlayer uses about 5 % CPU all the time. I'm sure I didn't have this issue before.

When interpreting my CPU load percentages, please note that I have a dual-core CPU and I don't use dividing the load by the number of cores, so both cores at full load would read as 200% usage in my case.

My HW conf:
Core2 T9550 2.66GHz
GF 9800M GTS
4GB RAM

MadCatX 09-01-10 04:33 PM

Re: Xorg high CPU usage on scrolling and moving windows
 
OK, perhaps I'm getting to the bottom of this. I ran the VDPAU benchmark from this forum and I found out that my results are way below average considering my HW configuration.

The result I got were like this:
Code:

qvdpautest 0.5.1
Intel(R) Core(TM)2 Duo CPU    T9550  @ 2.66GHz
NVIDIA GPU GeForce 9800M GTS (G94) at PCI:1:0:0 (GPU-0)

VDPAU API version : 1
VDPAU implementation : NVIDIA VDPAU Driver Shared Library  256.53  Fri Aug 27 20:54:24 PDT 2010

SURFACE GET BITS: 160.288 M/s
SURFACE PUT BITS: 79.8287 M/s

MPEG DECODING (1920x1080): 20 frames/s
MPEG DECODING (1280x720): 42 frames/s
H264 DECODING (1920x1080): 39 frames/s
H264 DECODING (1280x720): 86 frames/s
VC1 DECODING (1440x1080): 62 frames/s

MIXER WEAVE (1920x1080): 2086 frames/s
MIXER BOB (1920x1080): 3216 fields/s
MIXER TEMPORAL (1920x1080): 741 fields/s
MIXER TEMPORAL + IVTC (1920x1080): 385 fields/s
MIXER TEMPORAL + SKIP_CHROMA (1920x1080): 997 fields/s
MIXER TEMPORAL_SPATIAL (1920x1080): 228 fields/s
MIXER TEMPORAL_SPATIAL + IVTC (1920x1080): 176 fields/s
MIXER TEMPORAL_SPATIAL + SKIP_CHROMA (1920x1080): 249 fields/s
MIXER TEMPORAL_SPATIAL (720x576 video to 1920x1080 display): 772 fields/s

MULTITHREADED MPEG DECODING (1920x1080): 40 frames/s
MULTITHREADED MIXER TEMPORAL (1920x1080): 669 fields/s

That was done with compositing disabled. I ran the test multiple times, I even rebooted my machine to be 100% sure. Any ideas???

EDIT: The PUT/GET results seem to vary a lot, it can get as high as SURFACE GET BITS: 891.909 M/s
SURFACE PUT BITS: 908.877 M/s, but the decoding speed itself remains low no matter what.

zacbarton 09-01-10 07:25 PM

Re: Xorg high CPU usage on scrolling and moving windows
 
MadCatX check out http://www.nvnews.net/vbulletin/showthread.php?t=154563. The issue looks to be anti-aliasing related. I turned off anti-aliasing (changed to best contrast) and its solved the issue for me. Hopefully a proper fix is in the works?

MadCatX 09-01-10 07:52 PM

Re: Xorg high CPU usage on scrolling and moving windows
 
I've already tried that and antialiased fonts are not the problem in my case...

Arup 09-01-10 08:54 PM

Re: Xorg high CPU usage on scrolling and moving windows
 
KDE 4.5 turns on Blur effect by default, turn it off in desktop effects and all these issues will go away.

MadCatX 09-02-10 06:30 AM

Re: Xorg high CPU usage on scrolling and moving windows
 
I know about the issue with blur and as I said in my first post, this happens even without compositing, it also happens in plain X with TWM.

rtcm 09-02-10 06:41 AM

Re: Xorg high CPU usage on scrolling and moving windows
 
FWIW, I also noticed a slowdown in Firefox scrolling with the latest driver version.

MadCatX 09-02-10 07:09 AM

Re: Xorg high CPU usage on scrolling and moving windows
 
Can you check what's your CPU usage during the scrolling and compare it to you previous results or other apps? I have the latest beta of Firefox 4 too and it behaves pretty much the same as Opera which means slow...

Arup 09-02-10 09:31 AM

Re: Xorg high CPU usage on scrolling and moving windows
 
No scroll issues here with Opera on dual XEON with a 8400GS card.


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