The patch titled
Subject: cma: make default CMA area size zero for x86
has been added to the -mm tree. Its filename is
cma-make-default-cma-area-size-zero-for-x86.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/cma-make-default-cma-area-size-zero-for-x86.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/cma-make-default-cma-area-size-zero-for-x86.patch
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From: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Subject: cma: make default CMA area size zero for x86
This makes CMA memory area size zero for x86 in default configuration
(doesn't change on the other architectures). If default CMA size is zero,
DMA_CMA is disabled. It can be enabled by passing cma= to the kernel.
This makes less impact on x86. Because there is no mainline driver that
requires it for x86, and Peter Hurley reported the performance regression,
as this is trying to drive _all_ dma mapping allocations through a _very_
small window.
Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Reported-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Cc: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Cc: Chuck Ebbert <cebbert.lkml@xxxxxxxxx>
Cc: Jean Delvare <jdelvare@xxxxxxx>
Acked-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Don Dutile <ddutile@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/base/Kconfig | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff -puN drivers/base/Kconfig~cma-make-default-cma-area-size-zero-for-x86 drivers/base/Kconfig
--- a/drivers/base/Kconfig~cma-make-default-cma-area-size-zero-for-x86
+++ a/drivers/base/Kconfig
@@ -264,18 +264,24 @@ comment "Default contiguous memory area
config CMA_SIZE_MBYTES
int "Size in Mega Bytes"
depends on !CMA_SIZE_SEL_PERCENTAGE
+ default 0 if X86
default 16
help
Defines the size (in MiB) of the default memory area for Contiguous
- Memory Allocator.
+ Memory Allocator. If the size of 0 is selected, CMA is disabled by
+ default, but it can be enabled by passing cma=size[MG] to the kernel.
+
config CMA_SIZE_PERCENTAGE
int "Percentage of total memory"
depends on !CMA_SIZE_SEL_MBYTES
+ default 0 if X86
default 10
help
Defines the size of the default memory area for Contiguous Memory
Allocator as a percentage of the total memory in the system.
+ If 0 percent is selected, CMA is disabled by default, but it can be
+ enabled by passing cma=size[MG] to the kernel.
choice
prompt "Selected region size"
_
Patches currently in -mm which might be from akinobu.mita@xxxxxxxxx are
origin.patch
cma-make-default-cma-area-size-zero-for-x86.patch
linux-next.patch
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