Hi,
Could someone inform as to what is the behavior when madvise DONTNEED is
called on pages that are mmap'd from local files mapped with MAP_SHARED,
i.e. they share the same page that the file cache does. In such cases, can
madvise be made to release specific pages in the file cache by mmap-ing the
relevant file segment ?
thanks,
Muthian.
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"Muthian S" <[email protected]> wrote:
>
> Hi,
>
> Could someone inform as to what is the behavior when madvise DONTNEED is
> called on pages that are mmap'd from local files mapped with MAP_SHARED,
> i.e. they share the same page that the file cache does.
The pages are unmapped from the calling process's pagetables. We don't
actually free the physical pages.
> In such cases, can
> madvise be made to release specific pages in the file cache by mmap-ing the
> relevant file segment ?
No.
2.6 kernels implement the fadvise() syscall (accessible by glibc's
posix_fadvise() function) which will do this.
On Thu, Jul 31, 2003 at 03:32:11PM -0700, Andrew Morton wrote:
> "Muthian S" <[email protected]> wrote:
> >
> > Hi,
> >
> > Could someone inform as to what is the behavior when madvise DONTNEED is
> > called on pages that are mmap'd from local files mapped with MAP_SHARED,
> > i.e. they share the same page that the file cache does.
>
> The pages are unmapped from the calling process's pagetables. We don't
> actually free the physical pages.
>
> > In such cases, can
> > madvise be made to release specific pages in the file cache by mmap-ing the
> > relevant file segment ?
>
> No.
>
> 2.6 kernels implement the fadvise() syscall (accessible by glibc's
> posix_fadvise() function) which will do this.
Perhaps we could send the page to the least-used end of the page lists?
--
winden/network
1. Dado un programa, siempre tiene al menos un fallo.
2. Dadas varias lineas de codigo, siempre se pueden acortar a menos lineas.
3. Por induccion, todos los programas se pueden
reducir a una linea que no funciona.