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SubjectRe: [PATCH v4] zone_reclaim is always 0 by default
Acked-by: Robin Holt <>

On Thu, Jun 04, 2009 at 07:23:15PM +0900, KOSAKI Motohiro wrote:
> Actually, zone_reclaim_mode=1 mean "I dislike remote node allocation rather than
> disk access", it makes performance improvement to HPC workload.
> but it makes performance degression to desktop, file server and web server.

I still disagree with this statement, but I don't care that much.
Why not something more to the effect of:

Setting zone_reclaim_mode=1 causes memory allocations on a nearly
exhausted node to do direct reclaim within that node before attempting
off-node allocations. For work loads where most pages are clean in
page cache and easily reclaimed, this can result excessive disk activity
versus a more fair node memory balance.

If you disagree, don't respond, just ignore.

> --- a/include/linux/topology.h
> +++ b/include/linux/topology.h
> @@ -54,12 +54,7 @@ int arch_update_cpu_topology(void);
> #define node_distance(from,to) ((from) == (to) ? LOCAL_DISTANCE : REMOTE_DISTANCE)
> #endif
> -/*
> - * If the distance between nodes in a system is larger than RECLAIM_DISTANCE
> - * (in whatever arch specific measurement units returned by node_distance())
> - * then switch on zone reclaim on boot.
> - */
> -#define RECLAIM_DISTANCE 20

Why remove this comment? It seems more-or-less a reasonable statement.


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