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Sender: Tejun Heo <htejun@gmail.com>
Date: Tue, 20 Feb 2024 06:46:18 -1000
From: Tejun Heo <tj@kernel.org>
To: Xuewen Yan <xuewen.yan@unisoc.com>
Cc: jiangshanlai@gmail.com, corbet@lwn.net, paulmck@kernel.org,
	rdunlap@infradead.org, peterz@infradead.org, yanjiewtw@gmail.com,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	ke.wang@unisoc.com, xuewen.yan94@gmail.com
Subject: Re: [PATCH] workqueue: Control the frequency of intensive warning
 through cmdline
Message-ID: <ZdTXWrB8dascOIM_@slm.duckdns.org>
References: <20240219074634.2039-1-xuewen.yan@unisoc.com>
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In-Reply-To: <20240219074634.2039-1-xuewen.yan@unisoc.com>

Hello,

On Mon, Feb 19, 2024 at 03:46:34PM +0800, Xuewen Yan wrote:
> +#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT
> +static unsigned int wq_cpu_intensive_warning_per_count = 4;
> +module_param_named(cpu_intensive_warning_per_count, wq_cpu_intensive_warning_per_count, uint, 0644);
> +#endif

wq_cpu_intensive_warning_nth is probably shorter and more idiomatic.

> @@ -1202,7 +1206,7 @@ static void wq_cpu_intensive_report(work_func_t func)
>  		 * exponentially.
>  		 */
>  		cnt = atomic64_inc_return_relaxed(&ent->cnt);
> -		if (cnt >= 4 && is_power_of_2(cnt))
> +		if (wq_cpu_intensive_warning_per_count && !(cnt % wq_cpu_intensive_warning_per_count))

But aren't you mostly interested in the first report? Note that these events
can be very high frequency and reporting every nth event can lead to a lot
of constant warnings. Wouldn't it make sense to keep the exponential backoff
while allowing adjusting the initial threshold?

Thanks.

-- 
tejun