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authorAkinobu Mita <akinobu.mita@gmail.com>2014-12-11 02:43:14 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-11 04:41:06 +0300
commitd7be003a9d275299f5ee36bbdf156654f59e08e9 (patch)
treeb164b402af76a81eecd55cdddd1c23745fed9bef /drivers/base/Kconfig
parentc05543293e0bf586842844c14fd8c598f494a107 (diff)
downloadlinux-d7be003a9d275299f5ee36bbdf156654f59e08e9.tar.xz
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@gmail.com> Reported-by: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Chuck Ebbert <cebbert.lkml@gmail.com> Cc: Jean Delvare <jdelvare@suse.de> Acked-by: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Don Dutile <ddutile@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/base/Kconfig')
-rw-r--r--drivers/base/Kconfig8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index df04227d00cf..98504ec99c7d 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -267,18 +267,24 @@ comment "Default contiguous memory area size:"
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"