Messages in this thread | | | Subject | Re: [PATCH 00/28] Swap over NFS -v16 | From | Peter Zijlstra <> | Date | Tue, 26 Feb 2008 16:41:57 +0100 |
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On Tue, 2008-02-26 at 16:29 +0100, Miklos Szeredi wrote: > > > mm-page_file_methods.patch > > > > > > This makes page_offset and others more expensive by adding a > > > conditional jump to a function call that is not usually made. > > > > > > Why do swap pages have a different index to everyone else? > > > > Because the page->index of an anonymous page is related to its (anon)vma > > so that it satisfies the constraints for vm_normal_page(). > > > > The index in the swap file it totally unrelated and quite random. Hence > > the swap-cache uses page->private to store it in. > > Yeah, and putting the condition into page_offset() will confuse code > which uses it for finding the offset in the VMA
Right, do we do that anywhere?
> or in a tmpfs file.
Good point. I really should go read tmpfs some day, its really a blind spot for me.
> So why not just have a separate page_swap_offset() function, used > exclusively by swap_in/out()?
That would require duplicating quite a lot of NFS code from what I can see.
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