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Sender: Tejun Heo <htejun@gmail.com>
Date:   Wed, 21 Jun 2023 10:51:26 -1000
From:   Tejun Heo <tj@kernel.org>
To:     mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.co,
        vincent.guittot@linaro.org, linux-kernel@vger.kernel.org,
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        fuyuanli@didiglobal.com, zwp10758@gmail.com, zyhtheonly@gmail.com,
        zyhtheonly@yeah.net
Subject: Re: [PATCH v2] sched/isolation: add a workqueue parameter to
 constrain unbound CPUs
Message-ID: <ZJNizvI-7A2hFDoM@slm.duckdns.org>
References: <20230613092819.GA18487@didi-ThinkCentre-M930t-N000>
 <20230614091923.GA1059@didi-ThinkCentre-M930t-N000>
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In-Reply-To: <20230614091923.GA1059@didi-ThinkCentre-M930t-N000>
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On Wed, Jun 14, 2023 at 05:19:45PM +0800, tiozhang wrote:
...
> @@ -181,8 +181,8 @@ static int __init housekeeping_nohz_full_setup(char *str)
>  {
>  	unsigned long flags;
>  
> -	flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU |
> -		HK_FLAG_MISC | HK_FLAG_KTHREAD;
> +	flags = HK_FLAG_TICK | HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC
> +		| HK_FLAG_KTHREAD;

Why is WQ being taken out of nohz_full setup? The patch description doesn't
mention anything.

> @@ -208,6 +208,12 @@ static int __init housekeeping_isolcpus_setup(char *str)
>  			continue;
>  		}
>  
> +		if (!strncmp(str, "workqueue,", 10)) {
> +			str += 10;
> +			flags |= HK_FLAG_WQ;
> +			continue;
> +		}

I wonder whether it'd be better to just add a workqueue boot param but if
this works it's fine too.

Thanks.

-- 
tejun