Message-ID: <bfbdef64-1b8c-4168-2576-f6d4a112686b@redhat.com>
Date:   Wed, 15 Mar 2023 22:19:10 -0400
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Subject: Re: [PATCH] cgroup: fix display of forceidle time at root
Content-Language: en-US
To:     Josh Don <joshdon@google.com>, Tejun Heo <tj@kernel.org>,
        Zefan Li <lizefan.x@bytedance.com>,
        Johannes Weiner <hannes@cmpxchg.org>
Cc:     cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20230315214029.899573-1-joshdon@google.com>
From:   Waiman Long <longman@redhat.com>
In-Reply-To: <20230315214029.899573-1-joshdon@google.com>
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On 3/15/23 17:40, Josh Don wrote:
> We need to reset forceidle_sum to 0 when reading from root, since the
> bstat we accumulate into is stack allocated.
>
> To make this more robust, just replace the existing cputime reset with a
> memset of the overall bstat.
>
> Signed-off-by: Josh Don <joshdon@google.com>
> ---
>   kernel/cgroup/rstat.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
> index 831f1f472bb8..0a2b4967e333 100644
> --- a/kernel/cgroup/rstat.c
> +++ b/kernel/cgroup/rstat.c
> @@ -457,9 +457,7 @@ static void root_cgroup_cputime(struct cgroup_base_stat *bstat)
>   	struct task_cputime *cputime = &bstat->cputime;
>   	int i;
>   
> -	cputime->stime = 0;
> -	cputime->utime = 0;
> -	cputime->sum_exec_runtime = 0;
> +	memset(bstat, 0, sizeof(*bstat));
>   	for_each_possible_cpu(i) {
>   		struct kernel_cpustat kcpustat;
>   		u64 *cpustat = kcpustat.cpustat;

How about adding the following fixes tag?

Fixes: 1fcf54deb767 ("sched/core: add forced idle accounting for cgroups")

Cheers,
Longman