linux-kernel - Re: [PATCH] irq: better struct irqaction layout

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Date:	Thu, 4 Nov 2010 15:35:40 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] irq: better struct irqaction layout

On Thu, Nov 04, 2010 at 11:13:48AM +0100, Eric Dumazet wrote:
> We currently use kmalloc-96 slab for struct irqaction allocations on
> 64bit arches.
> 
> This is unfortunate because of possible false sharing and two cache
> lines accesses.
> 
> Move 'name' and 'dir' fields at the end of the structure, and force a
> suitable alignement.
> 
> Hot path fields now use one cache line on x86_64.

Looks good.  It would be nice if some of the fields could be merged (like
thread_flags and flags), but I assume it would be tought to get it back
to 64 bytes again.

Reviewed-by: Andi Kleen <ak@...ux.intel.com>
-Andi
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