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Subject[PATCH 0/6] mm: Remote LRU per-cpu pagevec cache/per-cpu page list drain support
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This series introduces an alternative locking scheme around mm/swap.c's per-cpu
LRU pagevec caches and mm/page_alloc.c's per-cpu page lists which will allow
for remote CPUs to drain them. Currently, only a local CPU is permitted to
change its per-cpu lists, and it's expected to do so, on-demand, whenever a
process demands it (by means of queueing an drain task on the local CPU). Most
systems will handle this promptly, but it'll cause problems for NOHZ_FULL CPUs
that can't take any sort of interruption without breaking their functional
guarantees (latency, bandwidth, etc...). Having a way for these processes to
remotely drain the lists themselves will make co-existing with isolated CPUs
possible, at the cost of more constraining locks.

Fortunately for non-NOHZ_FULL users, the alternative locking scheme and remote
drain code are conditional to a static key which is disabled by default. This
guarantees minimal functional or performance regressions. The feature will only
be enabled if NOHZ_FULL's initialization process was successful.

This work is based on a previous series by Thomas Gleixner, Anna-Maria
Gleixner, and Sebastian Andrzej Siewior[1].

[1] https://patchwork.kernel.org/project/linux-mm/patch/20190424111208.24459-3-bigeasy@linutronix.de/

Nicolas Saenz Julienne (6):
mm/swap: Introduce lru_cpu_needs_drain()
mm/swap: Introduce alternative per-cpu LRU cache locking
mm/swap: Allow remote LRU cache draining
mm/page_alloc: Introduce alternative per-cpu list locking
mm/page_alloc: Allow remote per-cpu page list draining
sched/isolation: Enable 'remote_pcpu_cache_access' on NOHZ_FULL
systems

kernel/sched/isolation.c | 9 +-
mm/internal.h | 2 +
mm/page_alloc.c | 111 ++++++++++++++++-----
mm/swap.c | 202 ++++++++++++++++++++++++++++++---------
4 files changed, 253 insertions(+), 71 deletions(-)

--
2.31.1

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