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Date:   Tue, 23 May 2023 08:52:26 +0800
From:   Yue Hu <zbestahu@gmail.com>
To:     Gao Xiang <hsiangkao@linux.alibaba.com>
Cc:     linux-erofs@lists.ozlabs.org, LKML <linux-kernel@vger.kernel.org>,
        Sandeep Dhavale <dhavale@google.com>, huyue2@coolpad.com,
        zhangwen@coolpad.com
Subject: Re: [PATCH] erofs: use HIPRI by default if per-cpu kthreads are
 enabled
Message-ID: <20230523085226.00006933.zbestahu@gmail.com>
In-Reply-To: <20230522092141.124290-1-hsiangkao@linux.alibaba.com>
References: <20230522092141.124290-1-hsiangkao@linux.alibaba.com>
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On Mon, 22 May 2023 17:21:41 +0800
Gao Xiang <hsiangkao@linux.alibaba.com> wrote:

> As Sandeep shown [1], high priority RT per-cpu kthreads are
> typically helpful for Android scenarios to minimize the scheduling
> latencies.
> 
> Switch EROFS_FS_PCPU_KTHREAD_HIPRI on by default if
> EROFS_FS_PCPU_KTHREAD is on since it's the typical use cases for
> EROFS_FS_PCPU_KTHREAD.
> 
> Also clean up unneeded sched_set_normal().
> 
> [1] https://lore.kernel.org/r/CAB=BE-SBtO6vcoyLNA9F-9VaN5R0t3o_Zn+FW8GbO6wyUqFneQ@mail.gmail.com
> Cc: Sandeep Dhavale <dhavale@google.com>
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
> ---
>  fs/erofs/Kconfig | 1 +
>  fs/erofs/zdata.c | 2 --
>  2 files changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/fs/erofs/Kconfig b/fs/erofs/Kconfig
> index 704fb59577e0..f259d92c9720 100644
> --- a/fs/erofs/Kconfig
> +++ b/fs/erofs/Kconfig
> @@ -121,6 +121,7 @@ config EROFS_FS_PCPU_KTHREAD
>  config EROFS_FS_PCPU_KTHREAD_HIPRI
>  	bool "EROFS high priority per-CPU kthread workers"
>  	depends on EROFS_FS_ZIP && EROFS_FS_PCPU_KTHREAD
> +	default y

How about removing this config option?

>  	help
>  	  This permits EROFS to configure per-CPU kthread workers to run
>  	  at higher priority.
> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> index 92f3a01262cf..3ba505434f03 100644
> --- a/fs/erofs/zdata.c
> +++ b/fs/erofs/zdata.c
> @@ -367,8 +367,6 @@ static struct kthread_worker *erofs_init_percpu_worker(int cpu)
>  		return worker;
>  	if (IS_ENABLED(CONFIG_EROFS_FS_PCPU_KTHREAD_HIPRI))
>  		sched_set_fifo_low(worker->task);
> -	else
> -		sched_set_normal(worker->task, 0);
>  	return worker;
>  }
>