Re: /dev/recycle

[Christoph Rohland <hans-christoph.rohland@sap.com>]

Jamie Lokier <lk@tantalophile.demon.co.uk> writes:

> Better than MADV_FREE: /dev/recycle
> --------------------------------------------------
> 
> What about this whacky idea?
> 
> MAP_RECYCLE|MAP_ANON initially allocates pages like MAP_ANON.  Mapping
> /dev/recycle is similar (but subtly different).
> 
> MADV_DONTNEED or munmap discard private modifications, but record this
> process as the page owner.  If the process later accesses the page, a
> page is allocated again but the MAP_RECYCLE means it may return a page
> already marked as belonging to this process without clearing it.
> 
> That's better for app allocators than MADV_FREE: they're giving the
> kernel more freedom with not much loss in performance.  And the kernel
> likes this too -- no need for vmscan to release references, as the pages
> are free already.

This would only work for /dev/zero like mappings. I need it for shm
mappings.

Greetings
		Christoph
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