Re: [RFC] /dev/anon

[Davide Libenzi]

On Wed, 14 Jan 2004, Jeff Dike wrote:

> > I thought your goal was to release memory 
> > to the host, that's why I proposed sys_madvise(MADV_DONTNEED).
> 
> It is, I want memory released immediately as though it were clean, and
> MADV_DONTNEED doesn't help.

Strange, I didn't notice this before. If you look at the comment in 
mm/madvise.c:madvise_dontneed, it advertises that dirty pages are actually 
thrown away (that would be what you're actually looking for). But if you 
go down to zap_page_range -> unmap_vmas -> unmap_page_range -> 
zap_pmd_range -> zap_pte_range, if the page is dirty, set_page_dirty -> 
__set_page_dirty_buffers pushes the page into the mapping dirty pages list 
and __mark_inode_dirty push the inode inside the superblock dirty list. So 
the comment seems to be wrong (I also verified this with a simple program, 
and pages are actually flushed).



- Davide






-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/