linux-kernel - [PATCH 1/3] mm, memcg: add mem_cgroup_disabled checks in vmpressure and swap-related functions

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Message-Id: <20210709000509.2618345-2-surenb@google.com>
Date:   Thu,  8 Jul 2021 17:05:07 -0700
From:   Suren Baghdasaryan <surenb@...gle.com>
To:     tj@...nel.org
Cc:     hannes@...xchg.org, mhocko@...nel.org, vdavydov.dev@...il.com,
        akpm@...ux-foundation.org, shakeelb@...gle.com, guro@...com,
        songmuchun@...edance.com, shy828301@...il.com, alexs@...nel.org,
        alexander.h.duyck@...ux.intel.com, richard.weiyang@...il.com,
        vbabka@...e.cz, axboe@...nel.dk, iamjoonsoo.kim@....com,
        david@...hat.com, willy@...radead.org, apopple@...dia.com,
        minchan@...nel.org, linmiaohe@...wei.com,
        linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
        linux-mm@...ck.org, kernel-team@...roid.com, surenb@...gle.com
Subject: [PATCH 1/3] mm, memcg: add mem_cgroup_disabled checks in vmpressure
 and swap-related functions

Add mem_cgroup_disabled check in vmpressure, mem_cgroup_uncharge_swap and
cgroup_throttle_swaprate functions. This minimizes the memcg overhead in
the pagefault and exit_mmap paths when memcgs are disabled using
cgroup_disable=memory command-line option.
This change results in ~2.1% overhead reduction when running PFT test
comparing {CONFIG_MEMCG=n, CONFIG_MEMCG_SWAP=n} against {CONFIG_MEMCG=y,
CONFIG_MEMCG_SWAP=y, cgroup_disable=memory} configuration on an 8-core
ARM64 Android device.

Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
---
 mm/memcontrol.c | 3 +++
 mm/swapfile.c   | 3 +++
 mm/vmpressure.c | 7 ++++++-
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ae1f5d0cb581..a228cd51c4bd 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7305,6 +7305,9 @@ void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
 	struct mem_cgroup *memcg;
 	unsigned short id;
 
+	if (mem_cgroup_disabled())
+		return;
+
 	id = swap_cgroup_record(entry, 0, nr_pages);
 	rcu_read_lock();
 	memcg = mem_cgroup_from_id(id);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 1e07d1c776f2..707fa0481bb4 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3778,6 +3778,9 @@ void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
 	struct swap_info_struct *si, *next;
 	int nid = page_to_nid(page);
 
+	if (mem_cgroup_disabled())
+		return;
+
 	if (!(gfp_mask & __GFP_IO))
 		return;
 
diff --git a/mm/vmpressure.c b/mm/vmpressure.c
index d69019fc3789..9b172561fded 100644
--- a/mm/vmpressure.c
+++ b/mm/vmpressure.c
@@ -240,7 +240,12 @@ static void vmpressure_work_fn(struct work_struct *work)
 void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
 		unsigned long scanned, unsigned long reclaimed)
 {
-	struct vmpressure *vmpr = memcg_to_vmpressure(memcg);
+	struct vmpressure *vmpr;
+
+	if (mem_cgroup_disabled())
+		return;
+
+	vmpr = memcg_to_vmpressure(memcg);
 
 	/*
 	 * Here we only want to account pressure that userland is able to
-- 
2.32.0.93.g670b81a890-goog