Re: [PATCH -mm 2/2] mm: kswapd carefully invoke compaction

[KOSAKI Motohiro]

> With CONFIG_COMPACTION enabled, kswapd does not try to free
> contiguous free pages, even when it is woken for a higher order
> request.
>
> This could be bad for eg. jumbo frame network allocations, which
> are done from interrupt context and cannot compact memory themselves.
> Higher than before allocation failure rates in the network receive
> path have been observed in kernels with compaction enabled.
>
> Teach kswapd to defragment the memory zones in a node, but only
> if required and compaction is not deferred in a zone.
>
> Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>

I agree with we need asynchronous defragmentations feature. But, do we
really need to use kswapd for compaction? While kswapd take a
compaction work, it can't work to make
free memory.
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