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Re: [Qemu-devel] [PATCH v4 0/9] Make 'dump-guest-memory' dump in kdump-c
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v4 0/9] Make 'dump-guest-memory' dump in kdump-compressed format |
Date: |
Mon, 1 Jul 2013 13:45:26 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Jun 28, 2013 at 10:57:28AM +0800, Qiao Nuohan wrote:
> On 06/27/2013 04:54 PM, Stefan Hajnoczi wrote:
> >
> >The interesting question is how effective this approach is. If it's
> >good enough then it would be a fairly simple modification to dump.c.
>
> I see, if excluding zero page in ELF can make a lot of size reduce, it's
> better
> to choose this method. But think over the situation that kernel is on for a
> long time, then few zero pages will be in memory, compression will do more
> work
> to reduce size not excluding zero pages. So the approach is not always
> effective.
>
> A test on a 1GB memory, and the machine is just on:
>
> size format method for reducing memory
>
> 1.1GB ELF no
> 1.1GB kdump no
> 227MB kdump with all zero pages excluded
> 96MB kdump compressed with zero pages remained
> 88MB kdump compressed with zero pages excluded
>
> excluding zero pages does some work, but compression seems to be more
> effective.
[...]
> >If it makes the code simpler and smaller it would be nice.
>
> That's the point. I will make the code simpler.
I'm now convinced that kdump is worthwhile, thanks for providing data.
It would be nice to see the flattened kdump approach.
Stefan
- Re: [Qemu-devel] [PATCH v4 0/9] Make 'dump-guest-memory' dump in kdump-compressed format,
Stefan Hajnoczi <=