Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII;
 format=flowed
Content-Transfer-Encoding: 7bit
Date:   Sat, 15 Aug 2020 15:29:41 +0100
From:   Marc Zyngier <maz@misterjones.org>
To:     Thomas Gleixner <tglx@linutronix.de>,
        Yunfeng Ye <yeyunfeng@huawei.com>
Cc:     Shiyuan Hu <hushiyuan@huawei.com>,
        Hewenliang <hewenliang4@huawei.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] genirq/affinity: show managed irq affinity correctly
In-Reply-To: <877du355o1.fsf@nanos.tec.linutronix.de>
References: <b55d8b8c-8afc-0046-44b6-514ad012936f@huawei.com>
 <877du355o1.fsf@nanos.tec.linutronix.de>
User-Agent: Roundcube Webmail/1.4.7
Message-ID: <11bb7a215cd8757f298d9f9608ed125c@misterjones.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 2020-08-13 09:08, Thomas Gleixner wrote:
> Yunfeng Ye <yeyunfeng@huawei.com> writes:

[...]

> You are looking at the wrong file. /proc/irq/$IRQ/smp_affinity* is the
> possible mask. If you want to know to which CPU an interrupt is affine
> then look at /proc/irq/$IRQ/effective_affinity*
> 
> If effective_affinity* is not showing the correct value, then the irq
> chip affinity setter is broken and needs to be fixed.

In order to reassure myself that nothing was untoward in GIC-land,
I went in and looked at an ITS-based VM running whatever is in
Linus' tree today. I see the effective affinity being correctly
setup, and being as expected a subset of the affinity. This is
without isolcpu though.

In any case, I'd be interested in understanding what this patch is
trying to solve, really.

         M.
-- 
Who you jivin' with that Cosmik Debris?