Date: Sat, 10 Dec 2005 04:32:35 +0100
From: Andi Kleen <ak@suse.de>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-kernel@vger.kernel.org, Hugh Dickins <hugh@veritas.com>,
       Nick Piggin <nickpiggin@yahoo.com.au>, linux-mm@kvack.org,
       Andi Kleen <ak@suse.de>, Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Subject: Re: [RFC 1/6] Framework
Message-ID: <20051210033235.GP11190@wotan.suse.de>
References: <20051210005440.3887.34478.sendpatchset@schroedinger.engr.sgi.com> <20051210005445.3887.94119.sendpatchset@schroedinger.engr.sgi.com>
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> +#define global_page_state(__x) atomic_long_read(&vm_stat[__x])
> +#define zone_page_state(__z,__x) atomic_long_read(&(__z)->vm_stat[__x])
> +extern unsigned long node_page_state(int node, enum zone_stat_item);
> +
> +/*
> + * For use when we know that interrupts are disabled.

Why do you need to disable interupts for atomic_t ? 
If you just want to prevent switching CPUs that could be 
done with get_cpu(), but alternatively you could just ignore
that race (it wouldn't be a big issue to still increment
the counter on the old CPU)

And why atomic and not just local_t?  On x86/x86-64 local_t
would be much cheaper at least. It's not long, but that could
be as well added.

-Andi

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