Messages in this thread | | | Date | Wed, 21 May 2014 19:49:11 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [patch -mm] mm, thp: avoid excessive compaction latency during fault fix |
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On Tue, 13 May 2014, Vlastimil Babka wrote:
> I wonder what about a process doing e.g. mmap() with MAP_POPULATE. It seems to > me that it would get only MIGRATE_ASYNC here, right? Since gfp_mask would > include __GFP_NO_KSWAPD and it won't have PF_KTHREAD. > I think that goes against the idea that with MAP_POPULATE you say you are > willing to wait to have everything in place before you actually use the > memory. So I guess you are also willing to wait for hugepages in that > situation? >
I don't understand the distinction you're making between MAP_POPULATE and simply a prefault of the anon memory. What is the difference in semantics between using MAP_POPULATE and touching a byte every page size along the range? In the latter, you'd be faulting thp with MIGRATE_ASYNC, so I don't understand how MAP_POPULATE is any different or implies any preference for hugepages.
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