From: Chris Metcalf <cmetcalf@mellanox.com>
To: Gilad Ben Yossef <giladb@ezchip.com>, Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Rik van Riel" <riel@redhat.com>, Tejun Heo <tj@kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Christoph Lameter <cl@linux.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Andy Lutomirski <luto@amacapital.net>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>
CC: Chris Metcalf <cmetcalf@mellanox.com>
Subject: [PATCH v12 03/13] lru_add_drain_all: factor out lru_add_drain_needed
Date: Tue, 5 Apr 2016 13:38:32 -0400
Message-ID: <1459877922-15512-4-git-send-email-cmetcalf@mellanox.com>
In-Reply-To: <1459877922-15512-1-git-send-email-cmetcalf@mellanox.com>
References: <1459877922-15512-1-git-send-email-cmetcalf@mellanox.com>
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This per-cpu check was being done in the loop in lru_add_drain_all(),
but having it be callable for a particular cpu is helpful for the
task-isolation patches.

Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>
---
 include/linux/swap.h |  1 +
 mm/swap.c            | 15 ++++++++++-----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index d18b65c53dbb..da21f5240702 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -304,6 +304,7 @@ extern void activate_page(struct page *);
 extern void mark_page_accessed(struct page *);
 extern void lru_add_drain(void);
 extern void lru_add_drain_cpu(int cpu);
+extern bool lru_add_drain_needed(int cpu);
 extern void lru_add_drain_all(void);
 extern void rotate_reclaimable_page(struct page *page);
 extern void deactivate_file_page(struct page *page);
diff --git a/mm/swap.c b/mm/swap.c
index 09fe5e97714a..bdcdfa21094c 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -653,6 +653,15 @@ void deactivate_page(struct page *page)
 	}
 }
 
+bool lru_add_drain_needed(int cpu)
+{
+	return (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
+		pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
+		pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
+		pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
+		need_activate_page_drain(cpu));
+}
+
 void lru_add_drain(void)
 {
 	lru_add_drain_cpu(get_cpu());
@@ -679,11 +688,7 @@ void lru_add_drain_all(void)
 	for_each_online_cpu(cpu) {
 		struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
 
-		if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
-		    pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
-		    pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
-		    pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
-		    need_activate_page_drain(cpu)) {
+		if (lru_add_drain_needed(cpu)) {
 			INIT_WORK(work, lru_add_drain_per_cpu);
 			schedule_work_on(cpu, work);
 			cpumask_set_cpu(cpu, &has_work);
-- 
2.7.2