2021-07-09 00:06:10

by Suren Baghdasaryan

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 <[email protected]>
---
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

2021-07-09 14:44:27

by Johannes Weiner

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

On Thu, Jul 08, 2021 at 05:05:07PM -0700, Suren Baghdasaryan wrote:
> 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 <[email protected]>

Acked-by: Johannes Weiner <[email protected]>

2021-07-09 16:02:48

by Shakeel Butt

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

On Thu, Jul 8, 2021 at 5:05 PM Suren Baghdasaryan <[email protected]> wrote:
>
[...]

> --- 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);

I was wondering why this was not crashing but realized that we
allocate root_mem_cgroup even in cgroup_disable=memory case.

Reviewed-by: Shakeel Butt <[email protected]>