RE: [patch 3/7] mm: vmscan: clarify how swappiness, highestpriority, memcg interact

[Satoru Moriya]

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@xxxxxxxxxxx>

Reviewed-by: Satoru Moriya <satoru.moriya@xxxxxxx>

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