Re: [uml-devel] uml-patch-2.4.22-7

[Matt Ayres <matta@tektonic.net>]

On Tue, 2003-12-16 at 17:55, Jeff Dike wrote:
> matta@tektonic.net said:
> > Well, when reboot/shutdown -r is run from within a UML it shuts down
> > and then states "INIT: no more processes in this runlevel" running
> > 2.4.22-um6.
> 
> Does it halt?
> 
> Where did you get your filesystem image?
> 
> I saw this a while back, and it turned out to be the filesystem.  The script
> that finally shuts the system down wasn't running, and the reason was that
> the running rc script called it through a link, and the link wasn't there.
> 

Yes, this was it.  The halt symlink was in runlevel 0 but not in 6.  I
guess I need to find a type to run "cd /etc/rc6.d && ln -sf
../init.d/halt S01reboot" inside each UML.  Thanks.

> > Is there a thread that I can be pointed to or a brief explanation of
> > how this is a benefit? 
> 
> The benefit is that when something does a 'sleep 1' inside UML, it will
> sleep for 1 second, and not 2 or 3 seconds.  There have been various complaints
> about this on the lists.
> 
> > ubd-mmap is new behavior that doesn't need to be enabled? (meaning,
> > just upgrade to -7 and we'll seen some better performance using the
> > block device) ?  
> 
> No, you have to turn it on (by adding ubd=mmap to the command line).
> 
> > Do you know how much performance is gained from
> > ubd-mmap and /dev/anon individually? 
> 
> It's not performance of an individual UML per se (the testing I've done shows
> that the performance is about the same), it's lower memory consumption on
> the host.  ubd-mmap eliminates the duplicate copies of data on the host (in
> the host page cache and the UML page cache) by mapping the host page cache
> directly into UML physical memory.  /dev/anon completes the picture by
> releasing the overmapped physical memory pages back to the host.
> 
> So, it'll increase your hosting capacity, and if the host is swapping, improve
> performance by keeping more UMLs in memory.
> 

Understood.
> 				Jeff
> 
> 
> 
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-- 
Matt Ayres <matta@tektonic.net>
TekTonic



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