linux-kernel - 答复: [外部邮件] Re: [PATCH] sched/cputime: Fix a mostly theoretical divide by zero

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Message-ID: <4709b236e32a41158994dae282f2be75@baidu.com>
Date: Tue, 17 Jun 2025 06:36:37 +0000
From: "Li,Rongqing" <lirongqing@...du.com>
To: Vincent Guittot <vincent.guittot@...aro.org>
CC: "mingo@...hat.com" <mingo@...hat.com>, "peterz@...radead.org"
	<peterz@...radead.org>, "juri.lelli@...hat.com" <juri.lelli@...hat.com>,
	"dietmar.eggemann@....com" <dietmar.eggemann@....com>, "rostedt@...dmis.org"
	<rostedt@...dmis.org>, "bsegall@...gle.com" <bsegall@...gle.com>,
	"mgorman@...e.de" <mgorman@...e.de>, "vschneid@...hat.com"
	<vschneid@...hat.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: 答复: [外部邮件] Re: [PATCH] sched/cputime: Fix a mostly theoretical divide by zero

> Theoretical is the right word; If all 2^32 possible threads belong to the process,
> we can get an overflow to 0 after ~4sec run time of each thread. But then how
> long will it take to have those 2^32 threads run 4sec on a system ...
> 
> It would be good to get number to show how realistic or not it could be to
> reach this value
> 
>

The 2^64 ns is 584 years, if a process with 1000 busy polling threads is running in a machine with more than 1000 CPUs, the runtime will overflow about half year

Thank
-LI