From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= <mans@mansr.com>
To: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Russell King <linux@arm.linux.org.uk>,
        LKML <linux-kernel@vger.kernel.org>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Nicolas Pitre <nico@linaro.org>, Tony Lindgren <tony@atomide.com>,
        Sebastian Frias <sebastian_frias@sigmadesigns.com>
Subject: Re: [PATCH] clocksource: Store reg field within struct clocksource
References: <564C8086.80804@sigmadesigns.com>
Date: Wed, 18 Nov 2015 13:51:04 +0000
In-Reply-To: <564C8086.80804@sigmadesigns.com> (Marc Gonzalez's message of
	"Wed, 18 Nov 2015 14:43:34 +0100")
Message-ID: <yw1xvb8zfmbb.fsf@unicorn.mansr.com>
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Marc Gonzalez <marc_gonzalez@sigmadesigns.com> writes:

> Since 'struct clocksource' is ____cacheline_aligned, gcc must insert
> a lot of padding between reg and clksrc in 'struct clocksource_mmio'
> (for example, L1_CACHE_BYTES = 64 on ARMv7).
>
> Storing reg within 'struct clocksource' removes unnecessary padding,
> and reg can then be grouped with other hot data.

Can you demonstrate a difference with this change?  Not saying it's bad,
but it's always good to have numbers.

> A nice side-effect of this patch is making container_of() unnecessary,
> which makes the code a bit simpler.

You really need to get used to that construct.

-- 
M?ns Rullg?rd
mans@mansr.com
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