Re: Active Memory Defragmentation: Our implementation & problems

[Alok Mooley <rangdi@xxxxxxxxx>]

--- "Richard B. Johnson" <root@chaos.analogic.com> >
If this is an Intel x86 machine, it is impossible
> for pages
> to get fragmented in the first place. The hardware
> allows any
> page, from anywhere in memory, to be concatenated
> into linear
> virtual address space. Even the kernel address space
> is virtual.
> The only time you need physically-adjacent pages is
> if you
> are doing DMA that is more than a page-length at a
> time. The
> kernel keeps a bunch of those pages around for just
> that
> purpose.
> 
> So, if you are making a "memory defragmenter", it is
> a CPU time-sink.
> That's all.

What if the external fragmentation increases so much
that it is not possible to find a large sized block?
Then, is it not better to defragment rather than swap
or fail?

-Alok

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