Performance of X (x11perf vs framebuffer vs test program)

Bilderbeek, Manuel manuel.bilderbeek at
Wed Apr 26 02:42:53 PDT 2006


I did some performance measurements again and I'd like to hear your

I did the following tests, all on an 800x600x16bpp configuration, on a
Via Epia ML, 800MHz on CLE266
1) fill 500x500 rectangles in the Linux framebuffer device, using a
memset for each line (see a previous mail on xorg mailinglist),
compilation with -O1
2) fill 500x500 rectangles with Java and Qt (didn't make a difference)
on X  (see a previous mail on xorg mailinglist)
3) use x11perf -rect500

I did these experiments both an a Debian testing system with Xorg 6.9
and a 2.6.15 kernel for 486, using fbdev and via drivers, and on a
MontaVista Linux (MVL) 4.0.1, with an Xorg 6.8.2 installation
(configured as 'tinyX', with only the fbdev driver) and a 2.6.10 kernel
tailored for Via C3.

The results are the number of 500x500 rectangle fills per second.

On Debian
1) 172
2) fbdev driver: 50, via driver (with hardware acceleration): more than
about 2000
3) fbdev driver: 169, via driver (with hardware acceleration): 3550
4) as 2), but with the Rotate "CW" option: fbdev (driver says: using
shadowfb): 23, via (driver says: hardware acceleration disabled, using
shadowfb): 40
5) as 3), but with the Rotate "CW" option: fbdev (as above): 124, via
(as above): 79

1) 190
2) fbdev driver: 59
3) fbdev driver: 230
4) as 2), but with the Rotate "CW" option (as above): fbdev: 20
5) as 3), but with the Rotate "CW" option (as above): fbdev: 193

Some things about this are quite weird in my eyes:
1) how can the x11perf program be faster than the C program with memset?
2) why is (on fbdev driver), the Qt/Java program more than a factor 3
slower (see previous mails about this, "Overhead of X11"), while all CPU
load is in X, according to atop?
3) in connection with 2): why is x11perf performing so much better than
the Qt/Java prog? Is this test comparable?
4) (most interesting for the OpenChrome folks) how on earth can the via
driver be 50% slower than the fbdev driver, when the Rotate option is

I'm not an in-depth X expert at all, that's why I'd like to ask for your
opinion once again... 

Kind regards,

Manuel Bilderbeek

This message and attachment(s) are intended solely for the use of the addressee and may contain information that is privileged, confidential or otherwise exempt from disclosure under applicable law.  
If you are not the intended recipient or agent thereof responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited.  
If you have received this communication in error, please notify the sender immediately by telephone and with a "reply" message.  
Thank you for your cooperation.

More information about the xorg mailing list