Re: [PATCH] clocksource: Store reg field within struct clocksource

From: Russell King - ARM Linux
Date: Wed Nov 18 2015 - 12:21:43 EST

On Wed, Nov 18, 2015 at 02:43:34PM +0100, Marc Gonzalez wrote:
> 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. A nice side-effect
> of this patch is making container_of() unnecessary, which makes the
> code a bit simpler.
> On 32-bit platforms, reg fits in the padding between read and mask,
> meaning no downside from storing it there.

Just swap the order of 'reg' and 'clksrc'.

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