linux-kernel - Re: [PATCH-cgroup] cgroup/cpuset: Fix incorrect top

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Date: Tue, 23 Apr 2024 21:02:52 -0400
From: Waiman Long <longman@...hat.com>
To: Tejun Heo <tj@...nel.org>, Zefan Li <lizefan.x@...edance.com>,
 Johannes Weiner <hannes@...xchg.org>
Cc: linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
 Xiu Jianfeng <xiujianfeng@...wei.com>, Xiu Jianfeng <xiujianfeng@...wei.com>
Subject: Re: [PATCH-cgroup] cgroup/cpuset: Fix incorrect top_cpuset flags


On 4/23/24 21:00, Waiman Long wrote:
> Commit 8996f93fc388 ("cgroup/cpuset: Statically initialize more
> members of top_cpuset") uses an incorrect "<" relational operator for
> the CS_SCHED_LOAD_BALANCE bit when initializing the top_cpuset. This
> results in load_balancing turned off by default in the top cpuset which
> is bad for performance.
>
> Fix this by using the BIT() helper macro to set the desired top_cpuset
> flags and avoid similar mistake from being made in the future.
>
> Fixes: 8996f93fc388 ("cgroup/cpuset: Statically initialize more members of top_cpuset")
> Signed-off-by: Waiman Long <longman@...hat.com>
> ---
>   kernel/cgroup/cpuset.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index e70008a1d86a..b0a97efa5f20 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -368,8 +368,8 @@ static inline void notify_partition_change(struct cpuset *cs, int old_prs)
>   }
>   
>   static struct cpuset top_cpuset = {
> -	.flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
> -		  (1 << CS_MEM_EXCLUSIVE) | (1 < CS_SCHED_LOAD_BALANCE)),
> +	.flags = BIT(CS_ONLINE) | BIT(CS_CPU_EXCLUSIVE) |
> +		 BIT(CS_MEM_EXCLUSIVE) | BIT(CS_SCHED_LOAD_BALANCE),
>   	.partition_root_state = PRS_ROOT,
>   	.relax_domain_level = -1,
>   	.remote_sibling = LIST_HEAD_INIT(top_cpuset.remote_sibling),
Add cc to xiujianfeng <xiujianfeng@...wei.com>