linux-kernel - Re: [rfc 00/45] [RFC] CPU ops and a rework of per cpu data handling on x86

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Message-Id: <20071119.200441.161851942.davem@davemloft.net>
Date:	Mon, 19 Nov 2007 20:04:41 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	ak@...e.de
Cc:	clameter@....com, akpm@...ux-foundation.org, travis@....com,
	mathieu.desnoyers@...ymtl.ca, linux-kernel@...r.kernel.org
Subject: Re: [rfc 00/45] [RFC] CPU ops and a rework of per cpu data
 handling on x86_64

From: Andi Kleen <ak@...e.de>
Date: Tue, 20 Nov 2007 04:25:34 +0100

> 
> > Although we have a per-cpu area base in a fixed global register
> > for addressing, the above isn't beneficial on sparc64 because
> > the atomic is much slower than doing a:
> >
> > 	local_irq_disable();
> > 	nonatomic_percpu_memory_op();
> > 	local_irq_enable();
> 
> Again might be pointing out the obvious, but you 
> need of course save_flags()/restore_flags(), not disable/enable().

Right, but the cost is the same for that on sparc64 unlike
x86 et al.
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