Messages in this thread | | | Date | Tue, 5 Aug 2008 12:11:48 +0100 | From | Mel Gorman <> | Subject | Re: [RFC] [PATCH 0/5 V2] Huge page backed user-space stacks |
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On (04/08/08 14:10), Dave Hansen didst pronounce: > On Thu, 2008-07-31 at 11:31 +0100, Mel Gorman wrote: > > We are a lot more reliable than we were although exact quantification is > > difficult because it's workload dependent. For a long time, I've been able > > to test bits and pieces with hugepages by allocating the pool at the time > > I needed it even after days of uptime. Previously this required a reboot. > > This is also a pretty big expansion of fs/hugetlb/ use outside of the > filesystem itself. It is hacking the existing shared memory > kernel-internal user to spit out effectively anonymous memory. > > Where do we draw the line where we stop using the filesystem for this? > Other than the immediate code reuse, does it gain us anything? > > I have to think that actually refactoring the filesystem code and making > it usable for really anonymous memory, then using *that* in these > patches would be a lot more sane. Especially for someone that goes to > look at it in a year. :) >
See, that's great until you start dealing with MAP_SHARED|MAP_ANONYMOUS. To get that right between children, you end up something very fs-like when the child needs to fault in a page that is already populated by the parent. I strongly suspect we end up back at hugetlbfs backing it :/
If you were going to do such a thing, you'd end up converting something like ramfs to hugetlbfs and sharing that.
-- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab
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