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Date:      Tue, 11 Apr 2006 12:08:49 -0700
From:      Bakul Shah <bakul@bitblocks.com>
To:        Joe Auty <joe@netmusician.org>
Cc:        freebsd-emulation@freebsd.org
Subject:   Re: Qemu pegging my CPU 
Message-ID:  <20060411190849.709B9294B3@mail.bitblocks.com>
In-Reply-To: Your message of "Tue, 11 Apr 2006 06:48:03 EDT." <CDC65463-FC8E-486C-B70D-32BC0A68C413@netmusician.org> 

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> It looks like Qemu just buggered up my networking so that it wasn't  
> accepting incoming requests to the entire FreeBSD machine (although  
> outgoing networking on that machine worked fine). Could this be  
> caused by lack of RAM too, or perhaps a problem with the Qemu kernel  
> module? I think I read somewhere else that it isn't always very stable?

kqemu seems reasonably stable now.

See if your disk activity light is brightly lit.  If so,
it is the swapping that is killing performance.  If it is not
lit, likely it is not hooked up:-) The disparity between the
swapping speed and processor speed is so much worse now that
pretty much any swapping will bring the machine to its knees.

You need at least as much memory as your working set.  So
either add more memory or reduce your working set by exiting
programs you can do without.  For instance remove web
browsers, email clients and bloaty window managers.  Reduce
memory needs of other things (for instance give less memory
to qemu but beware of the same issues for the virtual
machine!).  But as always *measure* the changes to better
understand the system behavior.

> I think I am running into swap... The answer sounds like adding more  
> RAM or more swap to the machine.

Adding more swap won't help.



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