Re: [PATCH] vmscan: evict use-once pages first (v3)

[Wu Fengguang <fengguang.wu@intel.com>]

On Sun, May 03, 2009 at 09:33:56AM +0800, Rik van Riel wrote:
> On Sun, 3 May 2009 09:15:40 +0800
> Wu Fengguang <fengguang.wu@intel.com> wrote:
> 
> > In the worse scenario, it could waste half the memory that could
> > otherwise be used for readahead buffer and to prevent thrashing, in a
> > server serving large datasets that are hardly reused, but still slowly
> > builds up its active list during the long uptime (think about a slowly
> > performance downgrade that can be fixed by a crude dropcache action).
> 
> In the best case, the active list ends up containing all the
> indirect blocks for the files that are occasionally reused,
> and the system ends up being able to serve its clients with
> less disk IO.
> 
> For systems like ftp.kernel.org, the files that are most
> popular will end up on the active list, without being kicked
> out by the files that are less popular.

Sure, such good cases tend to be prevalent - so obvious that I didn't
mind to mention ;-)