Messages in this thread | | | Date | Tue, 26 Sep 2017 10:51:27 +0100 | From | Mel Gorman <> | Subject | Re: [RFC 0/2] Use HighAtomic against long-term fragmentation |
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On Tue, Sep 26, 2017 at 04:46:42PM +0800, Hui Zhu wrote: > Current HighAtomic just to handle the high atomic page alloc. > But I found that use it handle the normal unmovable continuous page > alloc will help to against long-term fragmentation. >
This is not wise. High-order atomic allocations do not always have a smooth recovery path such as network drivers with large MTUs that have no choice but to drop the traffic and hope for a retransmit. That's why they have the highatomic reserve. If the reserve is used for normal unmovable allocations then allocation requests that could have waited for reclaim may cause high-order atomic allocations to fail. Changing it may allow improve latencies in some limited cases while causing functional failures in others. If there is a special case where there are a large number of other high-order allocations then I would suggest increasing min_free_kbytes instead as a workaround.
-- Mel Gorman SUSE Labs
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