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 6/6] sched/isolation: Enable 'remote_pcpu_cache_access' on NOHZ_FULL systems
Date: Tue, 21 Sep 2021 18:13:24 +0200 [thread overview]
Message-ID: <20210921161323.607817-7-nsaenzju@redhat.com> (raw)
In-Reply-To: <20210921161323.607817-1-nsaenzju@redhat.com>
When enabled, 'remote_pcpu_cache_access' allows for remote draining of
mm/swap.c's per-cpu LRU caches and mm/page_alloc.c's per-cpu page lists
instead of using per-cpu drain work. This comes at the cost of more
constraining locking, but NOHZ_FULL setups need this nonetheless:
processes running on isolated CPUs are sensitive to any sort of
interruption and preempting them in order to satisfy a housekeeping task
is bound to break their functional guarantees (i.e. latency, bandwidth,
etc...).
So enable 'remote_pcpu_cache_access' after having successfully
initialized NOHZ_FULL.
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>
---
kernel/sched/isolation.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 7f06eaf12818..4fc4c76f27ab 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -8,6 +8,7 @@
*
*/
#include "sched.h"
+#include "../../mm/internal.h"
DEFINE_STATIC_KEY_FALSE(housekeeping_overridden);
EXPORT_SYMBOL_GPL(housekeeping_overridden);
@@ -137,11 +138,17 @@ static int __init housekeeping_setup(char *str, enum hk_flags flags)
static int __init housekeeping_nohz_full_setup(char *str)
{
unsigned int flags;
+ int ret;
flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU |
HK_FLAG_MISC | HK_FLAG_KTHREAD;
- return housekeeping_setup(str, flags);
+ ret = housekeeping_setup(str, flags);
+ if (ret)
+ /* Avoid LRU cache and mm/page_alloc.c's pcplists drain work */
+ static_branch_enable(&remote_pcpu_cache_access);
+
+ return ret;
}
__setup("nohz_full=", housekeeping_nohz_full_setup);
--
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 ` [PATCH 5/6] mm/page_alloc: Allow remote per-cpu page list draining Nicolas Saenz Julienne
2021-09-21 16:13 ` Nicolas Saenz Julienne [this message]
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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