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SubjectRe: [PATCH 0/2] Disable zone_reclaim_mode by default
On Mon 07-04-14 23:34:26, Mel Gorman wrote:
> When it was introduced, zone_reclaim_mode made sense as NUMA distances
> punished and workloads were generally partitioned to fit into a NUMA
> node. NUMA machines are now common but few of the workloads are NUMA-aware
> and it's routine to see major performance due to zone_reclaim_mode being
> disabled but relatively few can identify the problem.
> Those that require zone_reclaim_mode are likely to be able to detect when
> it needs to be enabled and tune appropriately so lets have a sensible
> default for the bulk of users.
> Documentation/sysctl/vm.txt | 17 +++++++++--------
> include/linux/mmzone.h | 1 -
> mm/page_alloc.c | 17 +----------------
> 3 files changed, 10 insertions(+), 25 deletions(-)

Auto-enabling caused so many reports in the past that it is definitely
much better to not be clever and let admins enable zone_reclaim where it
is appropriate instead.

For both patches.
Acked-by: Michal Hocko <>
Michal Hocko

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