[PATCH][RFC] Allow explicit shrinking of arena heaps using an environment variable

[Jakub Jelinek]

On Fri, Jul 20, 2012 at 03:44:17PM -0700, Roland McGrath wrote:
> > I believe you are talking about the madvise mode that has been discussed a
> > few years ago, but unfortunately wasn't implemented in the end.
> 
> I was speaking in the abstract about what the interface contract for
> MADV_DONTNEED is and thus the range of behaviors that some kernel (Linux
> or otherwise) might one day implement.

If MADV_DONTNEED isn't any faster than munmap + mmap anymore (benchmarks?),
then here is a link to the MADV_FREE stuff that was being proposed and
discussed:
http://kerneltrap.org/mailarchive/linux-kernel/2007/4/17/77912
I believe the reason it hasn't been committed in the end was that
MADV_DONTNEED looked fast enough for the kernel people for the workloads
that were tested.  If that is not the case anymore and you can show
workloads where MADV_DONTNEED is too slow, perhaps it might be time to
attempt to ressurrect MADV_FREE, benchmark it and ask for inclusion...

	Jakub