Re: [PATCH -next] cgroup/cpuset: Statically initialize more members of top_cpuset

[Klara Modin <klarasmodin@gmail.com>]

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Hi,

On 2024-04-20 11:46, Xiu Jianfeng wrote:
> Initializing top_cpuset.relax_domain_level and setting
> CS_SCHED_LOAD_BALANCE to top_cpuset.flags in cpuset_init() could be
> completed at the time of top_cpuset definition by compiler.
> 
> Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
> ---
>   kernel/cgroup/cpuset.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index d8d3439eda4e..e70008a1d86a 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -369,8 +369,9 @@ 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_MEM_EXCLUSIVE) | (1 < CS_SCHED_LOAD_BALANCE)),

You dropped a '<' for the bitwise shift, this causes bad cpu utilization 
for me.

>   	.partition_root_state = PRS_ROOT,
> +	.relax_domain_level = -1,
>   	.remote_sibling = LIST_HEAD_INIT(top_cpuset.remote_sibling),
>   };
>   
> @@ -4309,8 +4310,6 @@ int __init cpuset_init(void)
>   	nodes_setall(top_cpuset.effective_mems);
>   
>   	fmeter_init(&top_cpuset.fmeter);
> -	set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
> -	top_cpuset.relax_domain_level = -1;
>   	INIT_LIST_HEAD(&remote_children);
>   
>   	BUG_ON(!alloc_cpumask_var(&cpus_attach, GFP_KERNEL));

Kind regards,
Klara Modin

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# bad: [a59668a9397e7245b26e9be85d23f242ff757ae8] Add linux-next specific files for 20240423
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# bad: [8996f93fc3880d000a0a0cb40c724d5830e140fd] cgroup/cpuset: Statically initialize more members of top_cpuset
git bisect bad 8996f93fc3880d000a0a0cb40c724d5830e140fd
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# first bad commit: [8996f93fc3880d000a0a0cb40c724d5830e140fd] cgroup/cpuset: Statically initialize more members of top_cpuset

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From dfc9b104bb62ac7d0546be445ce6add9e6d8c2fe Mon Sep 17 00:00:00 2001
From: Klara Modin <klarasmodin@gmail.com>
Date: Tue, 23 Apr 2024 21:00:56 +0200
Subject: [PATCH] cgroup/cpuset: fix bitwise shift in top_cpuset initialization

Fixes: 8996f93fc388 ("cgroup/cpuset: Statically initialize more members of top_cpuset")
Signed-off-by: Klara Modin <klarasmodin@gmail.com>
---
 kernel/cgroup/cpuset.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index e70008a1d86a..62d649d02f11 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -369,7 +369,7 @@ 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)),
+		  (1 << CS_MEM_EXCLUSIVE) | (1 << CS_SCHED_LOAD_BALANCE)),
 	.partition_root_state = PRS_ROOT,
 	.relax_domain_level = -1,
 	.remote_sibling = LIST_HEAD_INIT(top_cpuset.remote_sibling),
-- 
2.44.0