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Date: Thu, 2 Jul 2026 16:01:10 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: <wang.yaxin@zte.com.cn>
Cc: <fan.yu9@zte.com.cn>, <yang.yang29@zte.com.cn>, <corbet@lwn.net>,
 <linux-kernel@vger.kernel.org>, <linux-doc@vger.kernel.org>,
 <xu.xin16@zte.com.cn>
Subject: Re: [PATCH 2/3] delaytop: add timestamp of delay max
Message-Id: <20260702160110.789de3e4f12f28ae958ecea8@linux-foundation.org>
In-Reply-To: <20260702205854461V25Py2xQvLesD8HF_2Rh8@zte.com.cn>
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On Thu, 2 Jul 2026 20:58:54 +0800 (CST) <wang.yaxin@zte.com.cn> wrote:

> From: Wang Yaxin <wang.yaxin@zte.com.cn>
> 
> Record the wall-clock timestamp when each maximum delay occurred for
> all delay types. The timestamp is displayed in the MAX_TIMESTAMP column
> when using -t/--type option.
> 
> This enables:
> - Identifying the time when a process experienced an abnormal delay spike
> - Correlating delay peaks across multiple processes at the same timestamp
> - Cross-referencing with system logs, traces, or other metrics at that time
> - Pinpointing the root cause of latency issues by finding concurrent events
> 
> ...
> 
> +/*
> + * Format __kernel_timespec to human readable string (YYYY-MM-DDTHH:MM:SS)
> + * Returns formatted string or "N/A" if timestamp is zero
> + */
> +static const char *format_timespec64(struct __kernel_timespec *ts)
> +{
> +	static char buffer[32];
> +	time_t time_sec;
> +	struct tm tm_info;
> +
> +	/* Check if timestamp is zero (not set) */
> +	if (ts->tv_sec == 0 && ts->tv_nsec == 0)
> +		return "N/A";
> +
> +	/* Avoid Y2038 truncation: check if timestamp fits in time_t on 32-bit platforms */
> +	if (sizeof(time_t) < sizeof(ts->tv_sec) &&
> +	    ts->tv_sec > (__u64)((1ULL << (sizeof(time_t) * 8 - 1)) - 1))
> +		return "N/A";
> +
> +	time_sec = (time_t)ts->tv_sec;
> +
> +	if (localtime_r(&time_sec, &tm_info) == NULL)
> +		return "N/A";
> +
> +	snprintf(buffer, sizeof(buffer), "%04d-%02d-%02dT%02d:%02d:%02d",
> +		tm_info.tm_year + 1900,
> +		tm_info.tm_mon + 1,
> +		tm_info.tm_mday,
> +		tm_info.tm_hour,
> +		tm_info.tm_min,
> +		tm_info.tm_sec);
> +
> +	return buffer;
> +}

This appears to be a copy-paste-edit from format_timespec() in
tools/accounting/getdelays.c.  Why do the two differ?  Is it possible
to use a common implementation?  tools/accounting/format_tiomespec.o?

Does the getdelays.c version have the possible issue which AI review
identified?