Date: Wed, 29 Jul 2015 18:44:16 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, vikas.shivappa@intel.com, x86@kernel.org,
        hpa@zytor.com, tglx@linutronix.de, mingo@kernel.org, tj@kernel.org,
        matt.fleming@intel.com, will.auld@intel.com,
        glenn.p.williamson@intel.com, kanaka.d.juvva@intel.com
Subject: Re: [PATCH 1/9] x86/intel_cqm: Modify hot cpu notification handling
Message-ID: <20150729164416.GA25159@twins.programming.kicks-ass.net>
References: <1435789270-27010-1-git-send-email-vikas.shivappa@linux.intel.com>
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On Wed, Jul 01, 2015 at 03:21:02PM -0700, Vikas Shivappa wrote:
> +/*
> + * Temporary cpumask used during hot cpu notificaiton handling. The usage
> + * is serialized by hot cpu locks.
> + */
> +static cpumask_t tmp_cpumask;

So the problem with this is that its 512 bytes on your general distro
config. And this patch set includes at least 3 of them

So you've just shot 1k5 bytes of .data for no reason.

I know tglx whacked you over the head for this, but is this really worth
it? I mean, nobody sane should care about hotplug performance, so who
cares if we iterate a bunch of cpus on the abysmal slow path called
hotplug.
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