Re: how do file-mapped (mmapped) pages become dirty?

[Richard B. Johnson]

On Tue, 28 Oct 2003, Chris Friesen wrote:

> Helge Hafting wrote:
> > Amir Hermelin wrote:
>
> >> What function is responsible for this setting? And when will the page be
> >> written back to disk (i.e. where's the flusher located)?
> >>
> > When there's memory pressure, or a sync.
>
> Note however that you need an msync() -- fsync() and fdatasync() do not
> catch changes to mmapped pages.
>
> Chris
>

Sure they do. fsync() will sync the whole file, regardless of
whether or not it's been mapped. msync()  allows you to sync
only a  specific portion and control how that portion is
handled with some flags.

Cheers,
Dick Johnson
Penguin : Linux version 2.4.22 on an i686 machine (797.90 BogoMips).
            Note 96.31% of all statistics are fiction.


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