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SubjectRe: [PATCH -mm] make swapin readahead skip over holes
(1/9/12 6:10 PM), Rik van Riel wrote:
> Ever since abandoning the virtual scan of processes, for scalability
> reasons, swap space has been a little more fragmented than before.
> This can lead to the situation where a large memory user is killed,
> swap space ends up full of "holes" and swapin readahead is totally
> ineffective.
>
> On my home system, after killing a leaky firefox it took over an
> hour to page just under 2GB of memory back in, slowing the virtual
> machines down to a crawl.
>
> This patch makes swapin readahead simply skip over holes, instead
> of stopping at them. This allows the system to swap things back in
> at rates of several MB/second, instead of a few hundred kB/second.

If I understand correctly, this patch have

Pros
- increase IO throughput
Cons
- increase a risk to pick up unrelated swap entries by swap readahead


The changelog explained former but doesn't explained latter. I'm a bit
hesitate now.


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