Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 3 Apr 2018 12:25:56 +0200 (CEST)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Li RongQing <lirongqing@baidu.com>
cc:     LKML <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] genirq: only scan the present CPUs
In-Reply-To: <1522647902-11426-1-git-send-email-lirongqing@baidu.com>
Message-ID: <alpine.DEB.2.21.1804031224150.2511@nanos.tec.linutronix.de>
References: <1522647902-11426-1-git-send-email-lirongqing@baidu.com>
User-Agent: Alpine 2.21 (DEB 202 2017-01-01)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, 2 Apr 2018, Li RongQing wrote:

> lots of application will read /proc/stat, like ps and vmstat, but we
> find the reading time are spreading on Purley platform which has lots
> of possible CPUs and interrupt.
> 
> To reduce the reading time, only scan the present CPUs, not all possible
> CPUs, which speeds the reading of /proc/stat 20 times on Purley platform
> which has 56 present CPUs, and 224 possible CPUs

Why is BIOS/ACPI telling the kernel that there are 224 possible CPUs unless
it supports physical CPU hotplug.

Thanks,

	tglx