Re: [PATCH] dcache 2nd chance replacement

[Andrea Arcangeli <andrea@suse.de>]

On Thu, Jan 04, 2001 at 01:00:28PM -0200, Rik van Riel wrote:
> Other tasks tend not to stress the dcache like updatedb does,
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> leading to the effect that updatedb can "flush out" the other
> cached values faster than the other processes reference them.
> 
> This is something no amount of 2nd chance replacement or even
> aging can prevent.

Your arguments are senseless.

The dcache aging is mostly useful with _high_ VFS load like updatedb in
background. The logic is the same of the VM aging (ask yourself when the VM
aging is most useful: when there's high VM load, like a `cp /dev/zero .` in
background, the updatedb is the equivalent of `cp /dev/zero .` but for the
dcache).  Without the aging the "referenced" cache would be thrown away as well
with the rest of the cache pollution, while with the aging the "referenced"
cache will have a chance to remain in cache. This is true for both VM cache and
dcache.  The higher the load, the more times your working set would been thrown
away without the aging, so the higher improvement you get thanks to the aging.

Andrea
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