linux-kernel - [PATCH 2/2] x86: mtrr_cleanup try gran

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Date:	Mon, 29 Sep 2008 18:54:12 -0700
From:	Yinghai Lu <yhlu.kernel@...il.com>
To:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, Yinghai Lu <yhlu.kernel@...il.com>
Subject: [PATCH 2/2] x86: mtrr_cleanup try gran_size to less than 1M

one have gran < 1M

reg00: base=0xd8000000 (3456MB), size= 128MB: uncachable, count=1
reg01: base=0xe0000000 (3584MB), size= 512MB: uncachable, count=1
reg02: base=0x00000000 (   0MB), size=4096MB: write-back, count=1
reg03: base=0x100000000 (4096MB), size= 512MB: write-back, count=1
reg04: base=0x120000000 (4608MB), size= 128MB: write-back, count=1
reg05: base=0xd7f80000 (3455MB), size= 512KB: uncachable, count=1

will get

Found optimal setting for mtrr clean up
gran_size: 512K         chunk_size: 2M  num_reg: 7      lose RAM: 0G
range0: 0000000000000000 - 00000000d8000000
Setting variable MTRR 0, base: 0GB, range: 2GB, type WB
Setting variable MTRR 1, base: 2GB, range: 1GB, type WB
Setting variable MTRR 2, base: 3GB, range: 256MB, type WB
Setting variable MTRR 3, base: 3328MB, range: 128MB, type WB
hole: 00000000d7f00000 - 00000000d7f80000
Setting variable MTRR 4, base: 3455MB, range: 512KB, type UC
rangeX: 0000000100000000 - 0000000128000000
Setting variable MTRR 5, base: 4GB, range: 512MB, type WB
Setting variable MTRR 6, base: 4608MB, range: 128MB, type WB

so start from 64k instead of 1M

Signed-off-by: Yinghai Lu <yhlu.kernel@...il.com>
---
 arch/x86/kernel/cpu/mtrr/main.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Index: linux-2.6/arch/x86/kernel/cpu/mtrr/main.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/mtrr/main.c
+++ linux-2.6/arch/x86/kernel/cpu/mtrr/main.c
@@ -1197,11 +1197,11 @@ struct mtrr_cleanup_result {
 };
 
 /*
- * gran_size: 1M, 2M, ..., 2G
+ * gran_size: 64K, 128K, 256K, 512K, 1M, 2M, ..., 2G
  * chunk size: gran_size, ..., 2G
- * so we need (1+12)*6
+ * so we need (1+16)*8
  */
-#define NUM_RESULT	78
+#define NUM_RESULT	136
 #define PSHIFT		(PAGE_SHIFT - 10)
 
 static struct mtrr_cleanup_result __initdata result[NUM_RESULT];
@@ -1322,7 +1322,7 @@ static int __init mtrr_cleanup(unsigned
 	i = 0;
 	memset(min_loss_pfn, 0xff, sizeof(min_loss_pfn));
 	memset(result, 0, sizeof(result));
-	for (gran_size = (1ULL<<20); gran_size < (1ULL<<32); gran_size <<= 1) {
+	for (gran_size = (1ULL<<16); gran_size < (1ULL<<32); gran_size <<= 1) {
 		char gran_factor;
 		unsigned long gran_base;
 
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