[Xen-devel] Re: Reducing impact of save/restore/dump on Dom0

[Andi Kleen <ak@xxxxxxx>]

"Graham, Simon" <Simon.Graham@xxxxxxxxxxx> writes:

> Currently, save, restore and dump all used cached I/O in Dom0 to
> write/read the file containing the memory image of the DomU - when the
> memory assigned to the DomU is greater than free memory in Dom0, this
> leads to severe memory thrashing and generally the Dom0 performance goes
> into the toilet.
> 
> The 'classic' answer to avoiding this when writing very large files is,
> of course, to use non-cached I/O to manipulate the files - 

Otherwise you can just use madvise()/fadvise() to tell the kernel
to drop the old data [the later might need a fairly recent kernel
to work]

It has the advantage that it doesn't need much other changes.

-Andi

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