Re: [Qemu-devel] QEMU with KNOPPIX

From: Piotr Krysik <piotrek_priv@yahoo.com>
To: Kuniyasu Suzaki <k.suzaki@aist.go.jp>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] QEMU with KNOPPIX
Date: Thu, 26 Aug 2004 05:56:34 -0700 (PDT)	[thread overview]
Message-ID: <20040826125634.18345.qmail@web52507.mail.yahoo.com> (raw)
In-Reply-To: <1093500780.21464.780.camel@aragorn>

Hi,

Probably a lot of CPU is spend on decompressing 
in CLOOP driver. Maybe it could be possible to 
do decompression natively and not under emulated 
CPU.

You can start with an exercise. Setup CLOOP on 
your host (e.g. run Knoppix natively), then run 
another Knoppix inside Qemu, but give it access 
to your CLOOP device as an ide drive:
  qemu ... -cdrom /dev/cdrom -hda /dev/<your cloop>
Now try to use your host cloop device inside Qemu. 
E.g. mount it instead of guest cloop:
  mount ... /dev/hda <guest cloop mount point>
Play with it. If the performance difference 
is substantial, it may justify extra effort 
to implement cloop compatible Qemu disk format 
(I guess qcow is not compatible with cloop), 
so it can be used on Windows.

I didn't try this, so cannot guarantee that it 
will work. Contact me if you would like to try 
this and need assistance.

Regards,

Piotrek

--- "John R. Hogerhuis" <jhoger@pobox.com> wrote:

> On Wed, 2004-08-25 at 22:19, Kuniyasu Suzaki wrote:
> 
> > If you have any suggestions, please post.
> 
> Need to think of some ways to speed it up. It took
> several minutes to
> load.
> 
> Where are the possible optimizations?
> 
> Could we do a "save state" type operation and jump
> straight to loaded
> Knoppix desktop?
> 
> Seems to be a lot of CDROM activity. That is the
> nature of Knoppix, and
> that definitely slows Knoppix down, but for some
> reason it sounded
> really choppy to me. I'm wondering if there is
> anything we can do to
> speed up cd access. Maybe on a machine with a lot of
> RAM it could be
> read into RAM, or perhaps just copied to hard drive
> in one step and run
> from there. Some or all apps could be decompressed.
> I think Knoppix has
> something like this.
> 
> It's a complex set up, but some profiling might be
> in order... see how
> well QEMU translation cache is performing, and see
> if there is a lot of
> time spent in certain types of code that could be
> sped up in QEMU.
> 
> 
> I agree with you that Kazu's recent QEMU on Windows
> was indeed the heavy
> lifting, but there's still plenty to do on (Knoppix
> On (QEMU On
> Windows)) to make it really usable. Which I think it
> can be, and on some
> machines maybe it already is...
> 
> -- John.
> 
> 
> 
> 
> 
> 
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> 

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