On Wed, Nov 23, 2011 at 09:05:08PM +0800, Nai Xia wrote:

quoted

<SNIP>

Where are you adding this check?

If you mean in __unmap_and_move(), the check is unnecessary unless
another subsystem starts using sync-light compaction. With this series,
only direct compaction cares about MIGRATE_SYNC_LIGHT. If the page is

But I am still a little bit confused that if MIGRATE_SYNC_LIGHT is only
used by direct compaction and  another mode can be used by it:
MIGRATE_ASYNC also does not write dirty pages, then why not also
do an (current->flags & PF_MEMALLOC) test before writing out pages,

Why would it be necessary?
Why would it be better than what is there now?

like we already did for the page lock condition, but adding a new mode
instead?

I'm afraid I am missing the significance of your question or how it
might apply to the problem at hand.

-- 
Mel Gorman
SUSE Labs

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