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Date:   Mon, 24 Jan 2022 09:05:05 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Yury Norov <yury.norov@gmail.com>
Cc:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Andrew Morton <akpm@linux-foundation.org>,
        =?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= <mirq-linux@rere.qmqm.pl>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        David Laight <David.Laight@aculab.com>,
        Joe Perches <joe@perches.com>, Dennis Zhou <dennis@kernel.org>,
        Emil Renner Berthing <kernel@esmil.dk>,
        Nicholas Piggin <npiggin@gmail.com>,
        Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>,
        Alexey Klimov <aklimov@redhat.com>,
        linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Alison Schofield <alison.schofield@intel.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH 41/54] arch/x86: replace cpumask_weight with
 cpumask_weight_eq where appropriate
Message-ID: <20220124080505.GI20638@worktop.programming.kicks-ass.net>
References: <20220123183925.1052919-1-yury.norov@gmail.com>
 <20220123183925.1052919-42-yury.norov@gmail.com>
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On Sun, Jan 23, 2022 at 10:39:12AM -0800, Yury Norov wrote:
> smpboot code in somw places calls cpumask_weight() to compare the weight
> of cpumask with a given number. We can do it more efficiently with
> cpumask_weight_eq() because conditional cpumask_weight may stop traversing
> the cpumask earlier, as soon as condition is met.

Why use a more complicated API for code that has no performance
requirements?

From where I'm sitting this is a net negative for making the code harder
to read.