Re: statfs() / statvfs() syscall ballsup...

From: Helge Hafting
Date: Fri Oct 10 2003 - 15:25:18 EST


On Fri, Oct 10, 2003 at 11:05:35AM -0700, Joel Becker wrote:

> The problem we have with msync() and friends is not 'quick
> population', it's "page is in the page cache already; another node
> writes to the storage; must mark page as !uptodate so as to force a
> re-read from disk". I can't find where sys_readahead() checks for
> uptodate, so perhaps calling sys_readahead() on a range always causes
> I/O. Correct me if I missed it.
>

Wouldn't this be solvable by giving userspace a way of invalidating
a range of mmapped pages? I.e. a "minvalidate();" to use when
the other node tells you it is about to write?

This will cause the pages to be paged in again on next reference,
or you can issue a read in advance if you believe you'll need them.

Helge Hafting
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