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
