Hi,
Does anybody perhaps know why a DROPS virtual console focused on a L4Linux virtual console uses up CPU time? Is this "normal" behaviour? My DROPS console shows +- 25% CPU usage if the DROPS virtual console is focused on the L4Linux terminal, +- 1% if the DROPS virtual console is focused on something else (e.g. run console). From what I can tell, the thread running the L4Linux virtual console is at priority 0xff, but the main L4Linux task appears to be at default priority 0x10... Is this correct?
Thanks in advance, Bert
Hi,
On Thu Jun 23, 2005 at 22:25:31 +0200, Bert van Leeuwen wrote:
Does anybody perhaps know why a DROPS virtual console focused on a L4Linux virtual console uses up CPU time? Is this "normal" behaviour? My DROPS console shows +- 25% CPU usage if the DROPS virtual console is focused on the L4Linux terminal, +- 1% if the DROPS virtual console is focused on something else (e.g. run console). From what I can tell, the thread running the L4Linux virtual console is at priority 0xff, but the main L4Linux task appears to be at default priority 0x10... Is this correct?
If your L4Linx is 2.6 and you're using the l4fb driver, then the driver periodically refreshes the screen which costs CPU. You can switch that off by giving "l4fb.refreshsleep=0" at the kernel command line. But then user programs using the frame buffer (e.g. X) will not display anything. Maybe giving a bigger value will suit you better.
Adam
I'm using kernel 2.4, but I am using a framebuffer console, I will have a look into it.
Thanks, Bert
On 6/23/05, Adam Lackorzynski adam@os.inf.tu-dresden.de wrote:
Hi,
On Thu Jun 23, 2005 at 22:25:31 +0200, Bert van Leeuwen wrote:
Does anybody perhaps know why a DROPS virtual console focused on a
L4Linux
virtual console uses up CPU time? Is this "normal" behaviour? My DROPS console shows +- 25% CPU usage if the DROPS virtual console is focused
on
the L4Linux terminal, +- 1% if the DROPS virtual console is focused on something else (e.g. run console). From what I can tell, the thread
running
the L4Linux virtual console is at priority 0xff, but the main L4Linux
task
appears to be at default priority 0x10... Is this correct?
If your L4Linx is 2.6 and you're using the l4fb driver, then the driver periodically refreshes the screen which costs CPU. You can switch that off by giving "l4fb.refreshsleep=0" at the kernel command line. But then user programs using the frame buffer (e.g. X) will not display anything. Maybe giving a bigger value will suit you better.
Adam
Adam adam@os.inf.tu-dresden.de Lackorzynski http://os.inf.tu-dresden.de/~adam/
l4-hackers mailing list l4-hackers@os.inf.tu-dresden.de http://os.inf.tu-dresden.de/mailman/listinfo/l4-hackers
On Thu Jun 23, 2005 at 23:03:00 +0200, Bert van Leeuwen wrote:
I'm using kernel 2.4, but I am using a framebuffer console, I will have a look into it.
It's the same for 2.4 (actually the same driver).
Adam
How can I disable it? Do I just need to reconfigure the L4Linux kernel itself to remove framebuffer console support? I've changed my vbe mode to 512x384@16 instead of the 1024x768@16 it was on, and now uses only 10% CPU instead of 25%, so its definetely got something to do with the framebuffer console!
On 6/23/05, Adam Lackorzynski adam@os.inf.tu-dresden.de wrote:
On Thu Jun 23, 2005 at 23:03:00 +0200, Bert van Leeuwen wrote:
I'm using kernel 2.4, but I am using a framebuffer console, I will have
a
look into it.
It's the same for 2.4 (actually the same driver).
Adam
Adam adam@os.inf.tu-dresden.de Lackorzynski http://os.inf.tu-dresden.de/~adam/
l4-hackers mailing list l4-hackers@os.inf.tu-dresden.de http://os.inf.tu-dresden.de/mailman/listinfo/l4-hackers
On Thu Jun 23, 2005 at 23:33:35 +0200, Bert van Leeuwen wrote:
How can I disable it? Do I just need to reconfigure the L4Linux kernel itself to remove framebuffer console support? I've changed my vbe mode to 512x384@16 instead of the 1024x768@16 it was on, and now uses only 10% CPU instead of 25%, so its definetely got something to do with the framebuffer console!
Sure it has, I never said something else. To switch the refreshing off, use
video=l4fb:refreshsleep:0
at the kernel command line.
If you don't compile the driver in you won't see anything when using l4con.
Adam
On 6/23/05, Adam Lackorzynski adam@os.inf.tu-dresden.de wrote:
Sure it has, I never said something else.
;)
To switch the refreshing off, use
video=l4fb:refreshsleep:0
at the kernel command line.
If you don't compile the driver in you won't see anything when using l4con.
OK, that works as far as CPU usage is concerned, but (as advertised) I now no longer get any updates in my L4Linux console (i.e. it is blank permanently), so it is not usable anymore. Is there any way to have a text L4Linux console which does not use up CPU, or should I just not ever switch focus to the L4Linux framebuffer console?
On Fri Jun 24, 2005 at 00:00:37 +0200, Bert van Leeuwen wrote:
OK, that works as far as CPU usage is concerned, but (as advertised) I now no longer get any updates in my L4Linux console (i.e. it is blank permanently), so it is not usable anymore. Is there any way to have a text L4Linux console which does not use up CPU, or should I just not ever switch focus to the L4Linux framebuffer console?
I see now that 2.4 doesn't quite support all the feature like rectangular updates as 2.6 does. I.e. for 2.4 there are only full periodic updates possible, even for the console. One way could be to increase the sleep value to e.g. 1000 (1sec) instead of 0.
There's also a console driver in l4/pkg/l4con/examples/linux24_stub_lib that is supposed to work with 2.4 but I'm not sure it does right now. To use it, enable the CONFIG_L4_DROPSCON option in L4Linux so that it links to the stub lib.
Adam
Thanks for all your help Adam, I think I'll explore the 2.6 L4Linux kernel avenue first, since that is where I'd like to go in the long term anyway.
On 6/24/05, Adam Lackorzynski adam@os.inf.tu-dresden.de wrote:
On Fri Jun 24, 2005 at 00:00:37 +0200, Bert van Leeuwen wrote:
OK, that works as far as CPU usage is concerned, but (as advertised) I
now
no longer get any updates in my L4Linux console (i.e. it is blank permanently), so it is not usable anymore. Is there any way to have a
text
L4Linux console which does not use up CPU, or should I just not ever
switch
focus to the L4Linux framebuffer console?
I see now that 2.4 doesn't quite support all the feature like rectangular updates as 2.6 does. I.e. for 2.4 there are only full periodic updates possible, even for the console. One way could be to increase the sleep value to e.g. 1000 (1sec) instead of 0.
There's also a console driver in l4/pkg/l4con/examples/linux24_stub_lib that is supposed to work with 2.4 but I'm not sure it does right now. To use it, enable the CONFIG_L4_DROPSCON option in L4Linux so that it links to the stub lib.
Adam
Adam adam@os.inf.tu-dresden.de Lackorzynski http://os.inf.tu-dresden.de/~adam/
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