From f89112502805c1f6a6955f90ad158e538edb319d Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Fri, 4 Mar 2011 10:26:36 +0100
Subject: x86-64, NUMA: Revert NUMA affine page table allocation
This patch reverts NUMA affine page table allocation added by commit
1411e0ec31 (x86-64, numa: Put pgtable to local node memory).
The commit made an undocumented change where the kernel linear mapping
strictly follows intersection of e820 memory map and NUMA
configuration. If the physical memory configuration has holes or NUMA
nodes are not properly aligned, this leads to using unnecessarily
smaller mapping size which leads to increased TLB pressure. For
details,
http://thread.gmane.org/gmane.linux.kernel/1104672
Patches to fix the problem have been proposed but the underlying code
needs more cleanup and the approach itself seems a bit heavy handed
and it has been determined to revert the feature for now and come back
to it in the next developement cycle.
http://thread.gmane.org/gmane.linux.kernel/1105959
As init_memory_mapping_high() callsites have been consolidated since
the commit, reverting is done manually. Also, the RED-PEN comment in
arch/x86/mm/init.c is not restored as the problem no longer exists
with memblock based top-down early memory allocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/setup.c | 8 ++++++++
1 file changed, 8 insertions(+)
(limited to 'arch/x86/kernel/setup.c')
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 46e684f..c3a606c 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -963,6 +963,14 @@ void __init setup_arch(char **cmdline_p)
max_low_pfn_mapped = init_memory_mapping(0, max_low_pfn<<PAGE_SHIFT);
max_pfn_mapped = max_low_pfn_mapped;
+#ifdef CONFIG_X86_64
+ if (max_pfn > max_low_pfn) {
+ max_pfn_mapped = init_memory_mapping(1UL<<32,
+ max_pfn<<PAGE_SHIFT);
+ /* can we preseve max_low_pfn ?*/
+ max_low_pfn = max_pfn;
+ }
+#endif
memblock.current_limit = get_max_mapped();
/*
--
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