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From: Jakub Kicinski <kuba@kernel.org>
To: akpm@linux-foundation.org
Cc: linux-mm@kvack.org, kernel-team@fb.com, tj@kernel.org,
	hannes@cmpxchg.org, chris@chrisdown.name,
	cgroups@vger.kernel.org, shakeelb@google.com, mhocko@kernel.org,
	Jakub Kicinski <kuba@kernel.org>
Subject: [PATCH mm v6 1/4] mm: prepare for swap over-high accounting and penalty calculation
Date: Wed, 27 May 2020 12:58:43 -0700
Message-ID: <20200527195846.102707-2-kuba@kernel.org> (raw)
In-Reply-To: <20200527195846.102707-1-kuba@kernel.org>

Slice the memory overage calculation logic a little bit so we can
reuse it to apply a similar penalty to the swap. The logic which
accesses the memory-specific fields (use and high values) has to
be taken out of calculate_high_delay().

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/memcontrol.c | 62 ++++++++++++++++++++++++++++---------------------
 1 file changed, 35 insertions(+), 27 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f14da7a7348b..20ea7aea2292 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2302,41 +2302,48 @@ static void high_work_func(struct work_struct *work)
  #define MEMCG_DELAY_PRECISION_SHIFT 20
  #define MEMCG_DELAY_SCALING_SHIFT 14
 
-/*
- * Get the number of jiffies that we should penalise a mischievous cgroup which
- * is exceeding its memory.high by checking both it and its ancestors.
- */
-static unsigned long calculate_high_delay(struct mem_cgroup *memcg,
-					  unsigned int nr_pages)
+static u64 calculate_overage(unsigned long usage, unsigned long high)
 {
-	unsigned long penalty_jiffies;
-	u64 max_overage = 0;
-
-	do {
-		unsigned long usage, high;
-		u64 overage;
+	u64 overage;
 
-		usage = page_counter_read(&memcg->memory);
-		high = READ_ONCE(memcg->high);
+	if (usage <= high)
+		return 0;
 
-		if (usage <= high)
-			continue;
+	/*
+	 * Prevent division by 0 in overage calculation by acting as if
+	 * it was a threshold of 1 page
+	 */
+	high = max(high, 1UL);
 
-		/*
-		 * Prevent division by 0 in overage calculation by acting as if
-		 * it was a threshold of 1 page
-		 */
-		high = max(high, 1UL);
+	overage = usage - high;
+	overage <<= MEMCG_DELAY_PRECISION_SHIFT;
+	return div64_u64(overage, high);
+}
 
-		overage = usage - high;
-		overage <<= MEMCG_DELAY_PRECISION_SHIFT;
-		overage = div64_u64(overage, high);
+static u64 mem_find_max_overage(struct mem_cgroup *memcg)
+{
+	u64 overage, max_overage = 0;
 
-		if (overage > max_overage)
-			max_overage = overage;
+	do {
+		overage = calculate_overage(page_counter_read(&memcg->memory),
+					    READ_ONCE(memcg->high));
+		max_overage = max(overage, max_overage);
 	} while ((memcg = parent_mem_cgroup(memcg)) &&
 		 !mem_cgroup_is_root(memcg));
 
+	return max_overage;
+}
+
+/*
+ * Get the number of jiffies that we should penalise a mischievous cgroup which
+ * is exceeding its memory.high by checking both it and its ancestors.
+ */
+static unsigned long calculate_high_delay(struct mem_cgroup *memcg,
+					  unsigned int nr_pages,
+					  u64 max_overage)
+{
+	unsigned long penalty_jiffies;
+
 	if (!max_overage)
 		return 0;
 
@@ -2392,7 +2399,8 @@ void mem_cgroup_handle_over_high(void)
 	 * memory.high is breached and reclaim is unable to keep up. Throttle
 	 * allocators proactively to slow down excessive growth.
 	 */
-	penalty_jiffies = calculate_high_delay(memcg, nr_pages);
+	penalty_jiffies = calculate_high_delay(memcg, nr_pages,
+					       mem_find_max_overage(memcg));
 
 	/*
 	 * Don't sleep if the amount of jiffies this memcg owes us is so low
-- 
2.25.4



  reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-27 19:58 [PATCH mm v6 0/4] memcg: Slow down swap allocation as the available space gets depleted Jakub Kicinski
2020-05-27 19:58 ` Jakub Kicinski [this message]
2020-05-27 19:58 ` [PATCH mm v6 2/4] mm: move penalty delay clamping out of calculate_high_delay() Jakub Kicinski
2020-05-27 19:58 ` [PATCH mm v6 3/4] mm: move cgroup high memory limit setting into struct page_counter Jakub Kicinski
2020-05-27 19:58 ` [PATCH mm v6 4/4] mm: automatically penalize tasks with high swap use Jakub Kicinski
2020-05-27 20:05   ` Johannes Weiner
2020-06-04 15:57   ` Michal Hocko

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