From: Shakeel Butt <shakeelb@google.com>
To: Waiman Long <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Tejun Heo <tj@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
Cgroups <cgroups@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
Chris Down <chris@chrisdown.name>, Roman Gushchin <guro@fb.com>,
Yafang Shao <laoar.shao@gmail.com>
Subject: Re: [PATCH 3/3] mm/memcg: Unify swap and memsw page counters
Date: Thu, 20 Aug 2020 08:46:32 -0700 [thread overview]
Message-ID: <CALvZod7cNkjgd_YWzPSFm=AeC8sy5kWspX3J_Q7237Q9+N5Pxw@mail.gmail.com> (raw)
In-Reply-To: <20200820130350.3211-4-longman@redhat.com>
On Thu, Aug 20, 2020 at 6:04 AM Waiman Long <longman@redhat.com> wrote:
>
> The swap page counter is v2 only while memsw is v1 only. As v1 and v2
> controllers cannot be active at the same time, there is no point to keep
> both swap and memsw page counters in mem_cgroup. The previous patch has
> made sure that memsw page counter is updated and accessed only when in
> v1 code paths. So it is now safe to alias the v1 memsw page counter to v2
> swap page counter. This saves 14 long's in the size of mem_cgroup. This
> is a saving of 112 bytes for 64-bit archs.
>
> Signed-off-by: Waiman Long <longman@redhat.com>
> ---
> include/linux/memcontrol.h | 3 +--
> mm/memcontrol.c | 8 +++++---
> 2 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index d0b036123c6a..d2a819d7db70 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -216,10 +216,9 @@ struct mem_cgroup {
>
> /* Accounted resources */
> struct page_counter memory;
> - struct page_counter swap;
> + struct page_counter swap; /* memsw (memory+swap) for v1 */
>
> /* Legacy consumer-oriented counters */
> - struct page_counter memsw;
> struct page_counter kmem;
> struct page_counter tcpmem;
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index d219dca5239f..04c3794cdc98 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -68,6 +68,11 @@
>
> #include <trace/events/vmscan.h>
>
> +/*
> + * The v1 memsw page counter is aliased to the v2 swap page counter.
> + */
> +#define memsw swap
> +
Personally I would prefer a union instead of #define.
> struct cgroup_subsys memory_cgrp_subsys __read_mostly;
> EXPORT_SYMBOL(memory_cgrp_subsys);
>
> @@ -5279,13 +5284,11 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
> memcg->use_hierarchy = true;
> page_counter_init(&memcg->memory, &parent->memory);
> page_counter_init(&memcg->swap, &parent->swap);
> - page_counter_init(&memcg->memsw, &parent->memsw);
> page_counter_init(&memcg->kmem, &parent->kmem);
> page_counter_init(&memcg->tcpmem, &parent->tcpmem);
> } else {
> page_counter_init(&memcg->memory, NULL);
> page_counter_init(&memcg->swap, NULL);
> - page_counter_init(&memcg->memsw, NULL);
> page_counter_init(&memcg->kmem, NULL);
> page_counter_init(&memcg->tcpmem, NULL);
> /*
> @@ -5414,7 +5417,6 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
>
> page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX);
> page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX);
> - page_counter_set_max(&memcg->memsw, PAGE_COUNTER_MAX);
> page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX);
> page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX);
> page_counter_set_min(&memcg->memory, 0);
> --
> 2.18.1
>
next prev parent reply other threads:[~2020-08-20 15:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-20 13:03 [PATCH 0/3] mm/memcg: Miscellaneous cleanups and streamlining Waiman Long
2020-08-20 13:03 ` [PATCH 1/3] mm/memcg: Clean up obsolete enum charge_type Waiman Long
2020-08-20 17:27 ` Johannes Weiner
2020-08-20 21:16 ` Shakeel Butt
2020-08-20 13:03 ` [PATCH 2/3] mm/memcg: Simplify mem_cgroup_get_max() Waiman Long
2020-08-20 17:35 ` Johannes Weiner
2020-08-20 20:29 ` Waiman Long
2020-08-20 21:25 ` Shakeel Butt
2020-09-14 0:49 ` Waiman Long
2020-08-20 13:03 ` [PATCH 3/3] mm/memcg: Unify swap and memsw page counters Waiman Long
2020-08-20 15:46 ` Shakeel Butt [this message]
2020-08-24 16:02 ` Waiman Long
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