From: Nicolas Saenz Julienne <nsaenzju@redhat.com>
To: akpm@linux-foundation.org, frederic@kernel.org
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
tglx@linutronix.de, cl@linux.com, peterz@infradead.org,
juri.lelli@redhat.com, mingo@redhat.com, mtosatti@redhat.com,
nilal@redhat.com, mgorman@suse.de, ppandit@redhat.com,
williams@redhat.com, bigeasy@linutronix.de,
anna-maria@linutronix.de, linux-rt-users@vger.kernel.org,
Nicolas Saenz Julienne <nsaenzju@redhat.com>
Subject: [PATCH 3/6] mm/swap: Allow remote LRU cache draining
Date: Tue, 21 Sep 2021 18:13:21 +0200 [thread overview]
Message-ID: <20210921161323.607817-4-nsaenzju@redhat.com> (raw)
In-Reply-To: <20210921161323.607817-1-nsaenzju@redhat.com>
Some setups, notably NOHZ_FULL CPUs, are too busy to handle the per-cpu
drain work queued by __lru_add_drain_all(). So introduce new a mechanism
to remotely drain the per-cpu lists. It is made possible by using a more
constraining locking scheme, which is disabled by default and can be
enabled through the 'remote_pcpu_cache_access' static key. Regular users
shouldn't see any functional or performance change. Upcoming patches
will make use of the key.
Based on previous work by Thomas Gleixner, Anna-Maria Gleixner, and
Sebastian Andrzej Siewior[1].
[1] https://patchwork.kernel.org/project/linux-mm/cover/20190424111208.24459-1-bigeasy@linutronix.de/
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
---
mm/swap.c | 32 +++++++++++++++++++++-----------
1 file changed, 21 insertions(+), 11 deletions(-)
diff --git a/mm/swap.c b/mm/swap.c
index bcf73bd563a6..59e96a2520d5 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -915,19 +915,29 @@ inline void __lru_add_drain_all(bool force_all_cpus)
WRITE_ONCE(lru_drain_gen, lru_drain_gen + 1);
smp_mb();
- cpumask_clear(&has_work);
- for_each_online_cpu(cpu) {
- struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
-
- if (force_all_cpus || lru_cpu_needs_drain(cpu)) {
- INIT_WORK(work, lru_add_drain_per_cpu);
- queue_work_on(cpu, mm_percpu_wq, work);
- __cpumask_set_cpu(cpu, &has_work);
+ if (static_branch_unlikely(&remote_pcpu_cache_access)) {
+ for_each_online_cpu(cpu) {
+ if (force_all_cpus || lru_cpu_needs_drain(cpu)) {
+ lru_cache_lock_cpu(&lru_pvecs.locks, cpu);
+ lru_add_drain_cpu(cpu);
+ lru_cache_unlock_cpu(&lru_pvecs.locks, cpu);
+ }
+ }
+ } else {
+ cpumask_clear(&has_work);
+ for_each_online_cpu(cpu) {
+ struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
+
+ if (force_all_cpus || lru_cpu_needs_drain(cpu)) {
+ INIT_WORK(work, lru_add_drain_per_cpu);
+ queue_work_on(cpu, mm_percpu_wq, work);
+ __cpumask_set_cpu(cpu, &has_work);
+ }
}
- }
- for_each_cpu(cpu, &has_work)
- flush_work(&per_cpu(lru_add_drain_work, cpu));
+ for_each_cpu(cpu, &has_work)
+ flush_work(&per_cpu(lru_add_drain_work, cpu));
+ }
done:
mutex_unlock(&lock);
--
2.31.1
next prev parent reply other threads:[~2021-09-21 16:13 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-21 16:13 [PATCH 0/6] mm: Remote LRU per-cpu pagevec cache/per-cpu page list drain support Nicolas Saenz Julienne
2021-09-21 16:13 ` [PATCH 1/6] mm/swap: Introduce lru_cpu_needs_drain() Nicolas Saenz Julienne
2021-09-21 16:13 ` [PATCH 2/6] mm/swap: Introduce alternative per-cpu LRU cache locking Nicolas Saenz Julienne
2021-09-21 22:03 ` Peter Zijlstra
2021-09-22 8:47 ` nsaenzju
2021-09-22 9:20 ` Sebastian Andrzej Siewior
2021-09-22 9:50 ` nsaenzju
2021-09-22 11:37 ` Peter Zijlstra
2021-09-22 11:43 ` nsaenzju
2021-09-21 16:13 ` Nicolas Saenz Julienne [this message]
2021-09-21 16:13 ` [PATCH 4/6] mm/page_alloc: Introduce alternative per-cpu list locking Nicolas Saenz Julienne
2021-09-21 16:13 ` [PATCH 5/6] mm/page_alloc: Allow remote per-cpu page list draining Nicolas Saenz Julienne
2021-09-21 16:13 ` [PATCH 6/6] sched/isolation: Enable 'remote_pcpu_cache_access' on NOHZ_FULL systems Nicolas Saenz Julienne
2021-09-21 17:51 ` [PATCH 0/6] mm: Remote LRU per-cpu pagevec cache/per-cpu page list drain support Andrew Morton
2021-09-21 17:59 ` Vlastimil Babka
2021-09-22 11:28 ` Peter Zijlstra
2021-09-22 22:09 ` Thomas Gleixner
2021-09-23 7:12 ` Vlastimil Babka
2021-09-23 10:36 ` Thomas Gleixner
2021-09-27 9:30 ` nsaenzju
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