From: Andrew Morton <akpm@osdl.org>
To: colpatch@us.ibm.com
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
mbligh@aracnet.com, jbarnes@sgi.com
Subject: Re: [RFC] Simplify node/zone portion of page->flags
Date: Sun, 23 Nov 2003 14:40:52 -0800 [thread overview]
Message-ID: <20031123144052.1f0d5071.akpm@osdl.org> (raw)
In-Reply-To: <3FBEB867.9080506@us.ibm.com>
Matthew Dobson <colpatch@us.ibm.com> wrote:
>
> Currently we keep track of a pages node & zone in the top 8 bits (on
> 32-bit arches, 10 bits on 64-bit arches) of page->flags. We typically
> do: node_num * MAX_NR_ZONES + zone_num = 'nodezone'. It's non-trivial
> to break this 'nodezone' back into node and zone numbers. This patch
> modifies the way we compute the index to be: (node_num << ZONE_SHIFT) |
> zone_num. This makes it trivial to recover either the node or zone
> number with a simple bitshift. There are many places in the kernel
> where we do things like: page_zone(page)->zone_pgdat->node_id to
> determine the node a page belongs to. With this patch we save several
> pointer dereferences, and it boils down to shifting some bits.
This rather conflicts with the patch from Jesse which I have. Can you guys
work that out and let me know when you're done?
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next prev parent reply other threads:[~2003-11-23 22:40 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-22 1:14 Matthew Dobson
2003-11-23 22:40 ` Andrew Morton [this message]
2003-11-23 22:49 ` Jesse Barnes
2003-11-24 23:31 ` Jesse Barnes
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