Messages in this thread | | | Date | Thu, 29 Jul 1999 20:58:38 +0200 | From | Jamie Lokier <> | Subject | Re: clustering page-ins |
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Chuck Lever wrote: > true. but i'm also worried about sharing the read-ahead information > amongst all mappers of a shared file. this case has come up in my > benchmarking (although i haven't tracked it down, it is occurring in some > basic commands that are run by the benchmark).
Since each mapping has its own vm_area, I don't see the problem. Do you want different mappers to share read-ahead info?
> so, i think the information needs to be in the file struct so that shared > maps don't continue to read ahead a file that is already in the page > cache.
Sorry I don't quite understand what you want here. If you want to share read-ahead info between different mappers, struct file isn't going to do it -- each new open() creates a new struct file. If you don't, vm_area and struct file won't make much difference.
It's only when you consider multiple mappings made from the same file descriptor (or passed through fork/exec) that there's a difference: then struct file leads to sharing while vm_area does not. There's also the matter of files mapped and read with read() (e.g. ELF executables).
-- Jamie
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