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Subject[PATCH v5 0/2] Adjust NUMA imbalance for multiple LLCs
Date
Changelog since V4
o Scale imbalance based on the top domain that prefers siblings
o Keep allowed imbalance as 2 up to the point where LLCs can be overloaded

Changelog since V3
o Calculate imb_numa_nr for multiple SD_NUMA domains
o Restore behaviour where communicating pairs remain on the same node

Commit 7d2b5dd0bcc4 ("sched/numa: Allow a floating imbalance between NUMA
nodes") allowed an imbalance between NUMA nodes such that communicating
tasks would not be pulled apart by the load balancer. This works fine when
there is a 1:1 relationship between LLC and node but can be suboptimal
for multiple LLCs if independent tasks prematurely use CPUs sharing cache.

The series addresses two problems -- inconsistent logic when allowing a
NUMA imbalance and sub-optimal performance when there are many LLCs per
NUMA node.

include/linux/sched/topology.h | 1 +
kernel/sched/fair.c | 30 ++++++++++---------
kernel/sched/topology.c | 53 ++++++++++++++++++++++++++++++++++
3 files changed, 71 insertions(+), 13 deletions(-)

--
2.31.1

Mel Gorman (2):
sched/fair: Improve consistency of allowed NUMA balance calculations
sched/fair: Adjust the allowed NUMA imbalance when SD_NUMA spans
multiple LLCs

include/linux/sched/topology.h | 1 +
kernel/sched/fair.c | 30 ++++++++++---------
kernel/sched/topology.c | 53 ++++++++++++++++++++++++++++++++++
3 files changed, 71 insertions(+), 13 deletions(-)

--
2.31.1

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