Re: [PATCH 7/7] mm: compaction: add compaction to zone_reclaim_mode

[Hush Bensen <hush.bensen@gmail.com>]

Hi Andrea,
ao? 2013/7/13 0:01, Andrea Arcangeli a??e??:
> Hi,
>
> On Fri, Jul 12, 2013 at 06:26:37AM -0600, Hush Bensen wrote:
>>> This isn't VM reclaim, we're not globally low on memory and we can't
>>> wake kswapd until we expired all memory from all zones or we risk to
>>> screw the lru rotation even further (by having kswapd and the thread
>> What's the meaning of lru rotation?
> I mean the per-zone LRU walks to shrink the memory (they rotate pages
> through the LRU). To provide for better global working set information
> in the LRUs, we should walk all the zone LRUs in a fair
> way.
>
> zone_reclaim_mode however makes it non fair by always shrinking from
> the first NUMA local zone even if the other zones could be shrunk
> too.
>
> When zone_reclaim_mode is disabled instead (default for most hardware
> out there), we wait all candidate zones to be at the low wmark before
> starting the shrinking from any zone (and then we shrink all zones,
> not just one). So when zone_reclaim_mode is disabled, we don't insist
> aging a single zone indefinitely, while leaving the others un-aged.

Do you mean your patch done this fair? There is target zone shrink as 
you mentiond in the vanilla kernel, however, your patch also done target 
compaction/reclaim, is this fair?


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