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Vimal | 13 Aug 2010 09:15
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UML time dilation

Hi,

I wish to make time appear slower to applications running inside UML.
I came across this post:
http://www.mail-archive.com/user-mode-linux-user <at> lists.sourceforge.net/msg03984.html

But it looks like UML now uses hrtimers (setitimer, getitimer).  I
have configured a tickless kernel.

I tried dilating the time by library interposition and LD_PRELOADing a
module that modifies the following system calls:

- getitimer (gets the stored timer, returns T / dilation)
- setitimer (sets a new timer for T * dilation)
- nanosleep (sleeps for T * dilation)
- gtod: gettimeofday (returns T / dilation)

But some applications still have the correct knowledge of time.
Applications that use gtod still know the "real" time (though I
modified gtod), though "sleep 1" (which uses nanosleep), sleeps for 2
seconds.

Am I doing something wrong?

Thanks,
--

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Vimal

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Toralf Förster | 29 Aug 2010 19:22
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v2.6.36-rc3: UML compile error in hostaudio_kern.c

Hello,

I get with the attached config :

...
  CC      arch/um/drivers/hostaudio_kern.o
  CC      arch/um/kernel/tlb.o
  CC      arch/um/os-Linux/start_up.o
arch/um/drivers/hostaudio_kern.c: In function ‘hostaudio_open’:
arch/um/drivers/hostaudio_kern.c:204: error: ‘__param_dsp’ undeclared (first 
use in this function)
arch/um/drivers/hostaudio_kern.c:204: error: (Each undeclared identifier is 
reported only once
arch/um/drivers/hostaudio_kern.c:204: error: for each function it appears in.)
arch/um/drivers/hostaudio_kern.c: In function ‘hostmixer_open_mixdev’:
arch/um/drivers/hostaudio_kern.c:265: error: ‘__param_mixer’ undeclared (first 
use in this function)
arch/um/drivers/hostaudio_kern.c:272: error: ‘__param_dsp’ undeclared (first 
use in this function)
make[1]: *** [arch/um/drivers/hostaudio_kern.o] Error 1
make: *** [arch/um/drivers] Error 2
make: *** Waiting for unfinished jobs....

--

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MfG/Kind regards
Toralf Förster

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Sakari Ailus | 31 Aug 2010 00:17
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UML development, anyone?

Hello all,

I'm a long-time UML user and lately I've become a bit worried on the 
state of the UML. This list, as well as the -user one, is very quiet 
these days. Is there someone still actively developing the UML? I have 
to say I really like it! Running Linux on Linux reliably and 
efficiently, just what I need! :-)

I'm currently running three UML virtual machines on an server using 
Athlon XP-M. The host is running 2.6.31 and the guests are 2.6.27.

I cannot upgrade neither host nor guests due to these problems:

- SKAS 3 patches available up to 2.6.31 only. Merging this to current 
kernel might not be a problem, just some work, but:

- Severe data corruption on guest on recent guest kernel versions. I'm 
using a few hard disk partitions directly for UML guests. Something 
after 2.6.27 guest breaks this quite badly. Even for small data sets 
like 100 MiB, copying a file to a different location on guest and then 
running md5sum on both often produces a different result.

Do I have any options than to switch to Qemu and suffer the performance 
penalty from emulation (kqemu is obsolete, too) or to switch to newer 
hardware that supports kvm? Qemu performance is somewhat less than 10 % 
of the native (or UML) performance.

I also found something called lguest but haven't given it a try yet. 
Looks the most interesting but that doesn't seem to have much list 
activity either. So it works perfectly for almost everyone or has few
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