Subject: RE: [PATCH V2] arm64: psci: Reduce waiting time of cpu_psci_cpu_kill()

From: David Laight <[email-masked]>
Date: Thu, 17 Oct 2019 14:25:14 +0000

From: Yunfeng Ye
 > Sent: 17 October 2019 15:20
> On 2019/10/17 22:00, David Laight wrote:
> > From: Yunfeng Ye
> >> Sent: 17 October 2019 14:26
> > ...
> >>>> -	for (i = 0; i < 10; i++) {
> >>>> +	i = 0;
> >>>> +	timeout = jiffies + msecs_to_jiffies(100);
> >>>> +	do {
> >>>>  		err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
> >>>>  		if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
> >>>>  			pr_info("CPU%d killed.\n", cpu);
> >>>>  			return 0;
> >>>>  		}
> >>>>
> >>>> -		msleep(10);
> >>>> -		pr_info("Retrying again to check for CPU kill\n");
> >>>
> >>> You dropped this message, any particular reason ?
> >>>
> >> When reduce the time interval to 1ms, the print message maybe increase 10 times.
> >> on the other hand, cpu_psci_cpu_kill() will print message on success or failure, which
> >> this retry log is not very necessary. of cource, I think use pr_info_once() instead of
> >> pr_info() is better.
> >
> > Maybe you should print in on (say) the 10th time around the loop.
> >
> Can it like this:
>   pr_info("CPU%d killed with %d loops.\n", cpu, loops);
> 
> If put the number of waiting times in the successful printing message, it is
> not necessary to print the "Retrying ..." message.

That depends on whether you want to know how long it took or why the system
is 'stuck'.

	David

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