linux-kernel - Re: [PATCH 2/4] x86, numa: Do not adjust start/end for early_node

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Date:	Mon, 21 Feb 2011 09:21:27 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Tejun Heo <tj@...nel.org>
CC:	David Rientjes <rientjes@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Cyrill Gorcunov <gorcunov@...il.com>
Subject: Re: [PATCH 2/4] x86, numa: Do not adjust start/end for early_node_mem()

On 02/21/2011 01:43 AM, Tejun Heo wrote:
> Hello,
> 
> On Sat, Feb 19, 2011 at 08:17:11PM -0800, Yinghai Lu wrote:
>>> The old code guarantees that the range is from a single zone, and even
>>> though memblock may be top -> down, it seems like there would be
>>> configurations where this would still be an issue (perhaps simulating it
>>> with numa=fake for testing?) if it crosses the boundary.
>>
>> memblock_x86_find_in_range_node() will go over with early_node_map[].
>> so it will always can get right on node allocation.
> 
> I think always doing top-down allocation should be enough as long as
> there's no highmem, which we don't have on 64bit.  That said, the
> patch description should note the behavior difference.  Yinghai, care
> to add a bit more detail to the patch description?

please check

[PATCH] x86, numa, 64bit: Do not adjust start/end at first for early_node_mem()

We have top-down allocation  with memblock way now.
So do not need to adjust start/end to make them above DMA region.
memblock allocation always get high address for us.

Just remove those lines.

Signed-off-by: Yinghai Lu <yinghai@...nel.org>

---
 arch/x86/mm/numa_64.c |    9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

Index: linux-2.6/arch/x86/mm/numa_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/numa_64.c
+++ linux-2.6/arch/x86/mm/numa_64.c
@@ -164,14 +164,9 @@ static void * __init early_node_mem(int
 	unsigned long mem;
 
 	/*
-	 * put it on high as possible
-	 * something will go with NODE_DATA
+	 * memblock find will follow top-down. we will get addr above DMA region
+	 *  if possible, so don't need to adjust start anymore
 	 */
-	if (start < (MAX_DMA_PFN<<PAGE_SHIFT))
-		start = MAX_DMA_PFN<<PAGE_SHIFT;
-	if (start < (MAX_DMA32_PFN<<PAGE_SHIFT) &&
-	    end > (MAX_DMA32_PFN<<PAGE_SHIFT))
-		start = MAX_DMA32_PFN<<PAGE_SHIFT;
 	mem = memblock_x86_find_in_range_node(nodeid, start, end, size, align);
 	if (mem != MEMBLOCK_ERROR)
 		return __va(mem);

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