On 12/17/2012 01:12 PM, Johannes Weiner wrote:

A swappiness of 0 has a slightly different meaning for global reclaim 
(may swap if file cache really low) and memory cgroup reclaim (never 
swap, ever).

In addition, global reclaim at highest priority will scan all LRU 
lists equal to their size and ignore other balancing heuristics.
UNLESS swappiness forbids swapping, then the lists are balanced based 
on recent reclaim effectiveness.  UNLESS file cache is running low, 
then anonymous pages are force-scanned.

This (total mess of a) behaviour is implicit and not obvious from the 
way the code is organized.  At least make it apparent in the code flow 
and document the conditions.  It will be it easier to come up with 
sane semantics later.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Reviewed-by: Satoru Moriya <redacted>

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