On Tue, Dec 18, 2018 at 09:08:02AM +0100, Vlastimil Babka wrote: > On 12/15/18 12:03 AM, Mel Gorman wrote: > > Reserved pages are set at boot time, tend to be clustered and almost > > never become unreserved. When isolating pages for migrating, skip > > the entire pageblock is one PageReserved page is encountered on the > > grounds that it is highly probable the entire pageblock is reserved. > > Agreed, but maybe since it's highly probable and not certain, this > skipping should not be done on the highest compaction priority? > I don't think that's necessary at this time. For the most part, you are talking about one partial pageblock at best given how the early memory allocator works so it would only ever be useful for a high-order kernel allocation. Second, one of compactions primary problems is inefficient scanning where viable pageblocks are easily skipped over or only partially scanned which is something I'm still looking at. Lastly, maximum priority compaction is rarely hit in practice as far as I can tell. -- Mel Gorman SUSE Labs
