When it was introduced, zone_reclaim_mode made sense as NUMA distances^ I think you meant "enabled" here?
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(-)