linux-kernel - Re: [PATCH V2] arm64: psci: Reduce waiting time of cpu_psci_cpu

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Message-ID: <1cd555f0-4074-36b7-8426-6f01130051d2@huawei.com>
Date:   Thu, 17 Oct 2019 22:19:54 +0800
From:   Yunfeng Ye <yeyunfeng@...wei.com>
To:     David Laight <David.Laight@...LAB.COM>,
        Sudeep Holla <sudeep.holla@....com>
CC:     "catalin.marinas@....com" <catalin.marinas@....com>,
        "will@...nel.org" <will@...nel.org>,
        "kstewart@...uxfoundation.org" <kstewart@...uxfoundation.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "ard.biesheuvel@...aro.org" <ard.biesheuvel@...aro.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "wuyun.wu@...wei.com" <wuyun.wu@...wei.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "hushiyuan@...wei.com" <hushiyuan@...wei.com>,
        "linfeilong@...wei.com" <linfeilong@...wei.com>
Subject: Re: [PATCH V2] arm64: psci: Reduce waiting time of
 cpu_psci_cpu_kill()



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.

thanks.

> 	David
> 
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
>