makedumpfile memory usage grows with system memory size

[Atsushi Kumagai]

Hello Michael,

On Wed, 11 Apr 2012 10:04:03 +0200
Michael Holzheu <holzheu at linux.vnet.ibm.com> wrote:

> > bitmap file is main cause of memory consuming if 2nd kernel uses initramfs
> > only. There are other parts where the size of allocated memory varies based
> > on 1-st kernel memory size, but they don't have big influence.
> 
> Thanks for the explanation. 
> 
> I ask because I want to exactly calculate the required size for the
> crashkernel parameter. On s390 the kdump kernel memory consumption is
> fix and not dependent on the 1st kernel memory size. So based on your
> explanation I, will use:
> 
> crashkernel=<base size> + <variable size>
> 
> where
> 
> <variable size> = <pages of 1st kernel> * (2 + x) / 8
> 
> where "x" is the variable makedumpfile memory allocation that is on top
> of the bitmap allocation. What would be a good value for "x"?

I'm sorry that I don't have the exact number, but even the second biggest
memory allocation would require under 1/100 of the bitmap size, so, I think
0.01 is usually enough for "x".

Thanks
Atsushi Kumagai