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 5/6] mm/page_alloc: Allow remote per-cpu page list draining
Date: Tue, 21 Sep 2021 18:13:23 +0200 [thread overview]
Message-ID: <20210921161323.607817-6-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 __drain_all_pages(). 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 static key.
This is based on previous work 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/
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
---
mm/page_alloc.c | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3244eb2ab51b..717df675ea06 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3268,15 +3268,25 @@ static void __drain_all_pages(struct zone *zone, bool force_all_cpus)
cpumask_clear_cpu(cpu, &cpus_with_pcps);
}
- for_each_cpu(cpu, &cpus_with_pcps) {
- struct pcpu_drain *drain = per_cpu_ptr(&pcpu_drain, cpu);
+ if (static_branch_unlikely(&remote_pcpu_cache_access)) {
+ for_each_cpu(cpu, &cpus_with_pcps) {
+ if (zone) {
+ drain_pages_zone(cpu, zone);
+ } else {
+ drain_pages(cpu);
+ }
+ }
+ } else {
+ for_each_cpu(cpu, &cpus_with_pcps) {
+ struct pcpu_drain *drain = per_cpu_ptr(&pcpu_drain, cpu);
- drain->zone = zone;
- INIT_WORK(&drain->work, drain_local_pages_wq);
- queue_work_on(cpu, mm_percpu_wq, &drain->work);
+ drain->zone = zone;
+ INIT_WORK(&drain->work, drain_local_pages_wq);
+ queue_work_on(cpu, mm_percpu_wq, &drain->work);
+ }
+ for_each_cpu(cpu, &cpus_with_pcps)
+ flush_work(&per_cpu_ptr(&pcpu_drain, cpu)->work);
}
- for_each_cpu(cpu, &cpus_with_pcps)
- flush_work(&per_cpu_ptr(&pcpu_drain, cpu)->work);
mutex_unlock(&pcpu_drain_mutex);
}
--
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 ` [PATCH 3/6] mm/swap: Allow remote LRU cache draining Nicolas Saenz Julienne
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 ` Nicolas Saenz Julienne [this message]
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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