On 01/11/2012 02:25 AM, KOSAKI Motohiro wrote:
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.
I believe we do need some background compaction, especially
to help allocations from network interrupts.
If you believe the compaction is better done from some
other thread, I guess we could do that, but truthfully, if
kswapd spends a lot of time doing compaction, I made a
mistake somewhere :)
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