Messages in this thread | | | Date | Thu, 25 Sep 2008 00:42:13 +0100 | From | Mel Gorman <> | Subject | Re: [PATCH 1/2] Report the pagesize backing a VMA in /proc/pid/smaps |
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On (24/09/08 12:23), Dave Hansen didst pronounce: > On Wed, 2008-09-24 at 20:11 +0100, Mel Gorman wrote: > > I don't get what you mean by it being sprinkled in each smaps file. How > > would you present the data? > > 1. figure out what the file path is from smaps > 2. look up the mount > 3. look up the page sizes from the mount's information > > > > We should be able to figure out which > > > mount the file is from and, from there, maybe we need some per-mount > > > information exported. > > > > Per-mount information is already exported and you can infer the data about > > huge pagesizes. For example, if you know the default huge pagesize (from > > /proc/meminfo), and the file is on hugetlbfs (read maps, then /proc/mounts) > > and there is no pagesize= mount option (mounts again), you could guess what the > > hugepage that is backing a VMA is. Shared memory segments are a little harder > > but again, you can infer the information if you look around for long enough. > > > > However, this is awkward and not very user-friendly. With the patches (minus > > MMUPageSize as I think we've agreed to postpone that), it's easy to see what > > pagesize is being used at a glance. Without it, you need to know a fair bit > > about hugepages are implemented in Linux to infer the information correctly. > > I agree completely. But, if we consider this a user ABI thing, then > we're stuck with it for a long time, and we better make it flexible > enough to at least contain the gunk we're planning on adding in a small > number of years, like the fallback. We don't want to be adding this > stuff if it isn't going to be stable. >
This could also be done as
KernelPageSize == Kernel page size that is ideally used in this VMA
and later
MixedPageSize == Breakdown of the pagesizes that are used in the VMA
-- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab
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