Re: [PATCH/DESCRIPTION 7/7] unevictable lru: replace patch description

KOSAKI Motohiro
2008-07-30T20:48:26Z

> Christoph Lameter pointed out that ram disk pages also clutter the LRU
> lists. When vmscan finds them dirty and tries to clean them, the ram disk
> writeback function just redirties the page so that it goes back onto the
> active list. Round and round she goes...
>
> With the ram disk driver [rd.c] replaced by the newer 'brd.c', this is
> no longer the case, as ram disk pages are no longer maintained on the
> lru. [This makes them unmigratable for defrag or memory hot remove,
> but that can be addressed by a separate patch series.] However, the
> ramfs pages behave like ram disk pages used to, so:
>
> Define new address_space flag [shares address_space flags member with
> mapping's gfp mask] to indicate that the address space contains all
> unevictable pages. This will provide for efficient testing of ramfs
> pages in page_evictable().
>
> Also provide wrapper functions to set/test the unevictable state to
> minimize #ifdefs in ramfs driver and any other users of this facility.
>
> Set the unevictable state on address_space structures for new ramfs
> inodes. Test the unevictable state in page_evictable() to cull
> unevictable pages.
>
> These changes depend on [CONFIG_]UNEVICTABLE_LRU.

looks good to me.
but I can't believe my english skill.....