From: Shakeel Butt <shakeel.butt@linux.dev>
To: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Muchun Song <muchun.song@linux.dev>,
kernel test robot <oliver.sang@intel.com>
Subject: Re: [PATCH] mm: memcg: add cacheline padding after lruvec in mem_cgroup_per_node
Date: Tue, 23 Jul 2024 10:30:31 -0700 [thread overview]
Message-ID: <4xrfzyqmmq5gmowvyxxqn2xogo4o3rktc2btces3zeamhnaoxz@kor2cgbm46ou> (raw)
In-Reply-To: <20240723171244.747521-1-roman.gushchin@linux.dev>
On Tue, Jul 23, 2024 at 05:12:44PM GMT, Roman Gushchin wrote:
> Oliver Sand
Oliver Sang
> reported a performance regression caused by
> commit 98c9daf5ae6b ("mm: memcg: guard memcg1-specific members of struct
> mem_cgroup_per_node"), which puts some fields of the
> mem_cgroup_per_node structure under the CONFIG_MEMCG_V1 config option.
> Apparently it causes a false cache sharing between lruvec and
> lru_zone_size members of the structure. Fix it by adding an explicit
> padding after the lruvec member.
>
> Even though the padding is not required with CONFIG_MEMCG_V1 set,
> it seems like the introduced memory overhead is not significant
> enough to warrant another divergence in the mem_cgroup_per_node
> layout, so the padding is added unconditionally.
>
> Fixes: 98c9daf5ae6b ("mm: memcg: guard memcg1-specific members of struct mem_cgroup_per_node")
> Reported-by: kernel test robot <oliver.sang@intel.com>
> Closes: https://lore.kernel.org/oe-lkp/202407121335.31a10cb6-oliver.sang@intel.com
> Tested-by: Oliver Sang <oliver.sang@intel.com>
> Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
prev parent reply other threads:[~2024-07-23 17:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-23 17:12 Roman Gushchin
2024-07-23 17:30 ` Shakeel Butt [this message]
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