linux-kernel - Re: [PATCH] genirq/proc: Show percpu irq affinity

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Date:   Tue, 25 Aug 2020 17:39:44 +0800
From:   Yunfeng Ye <yeyunfeng@...wei.com>
To:     Thomas Gleixner <tglx@...utronix.de>
CC:     <linux-kernel@...r.kernel.org>, Shiyuan Hu <hushiyuan@...wei.com>,
        Hewenliang <hewenliang4@...wei.com>,
        Marc Zyngier <maz@...nel.org>
Subject: Re: [PATCH] genirq/proc: Show percpu irq affinity



On 2020/8/22 19:35, Thomas Gleixner wrote:
> On Sat, Aug 22 2020 at 17:33, Yunfeng Ye wrote:
>> On 2020/8/13 16:27, Thomas Gleixner wrote:
>> For example, the cmdline "irqaffinity=0,1,126,127" on the 128 cores system：
>>
>> [root@...alhost ~]# cat /proc/irq/4/smp_affinity_list
>> 0-1,126-127
>>
>> The irq 4 is "arch_timer" interrupt, which is a percpu interrupt.
>>
>> So is it necessary to show the percpu irq affinity correct?
> 
> Yes, it makes sense to do so, but you used the wrong check. The correct
> one is:
> 
> irq_settings_is_per_cpu_devid()
> 
> which will not wreckage the output for other per cpu marked interrupts
> which never set the percpu_affinity pointer with the obvious
> consequences... The pointer would need a NULL check in any case, but it
> might be more straight forward to update affinity when percpu_affinity
> is initialized. Haven't looked in detail though.
> 
ok, I will send the patch v2, thanks.

> Thanks,
> 
>         tglx
> 
> .
>