The patch titled
Subject: mmKconfig: add an option to disable bounce
has been added to the -mm tree. Its filename is
mmkconfig-add-an-option-to-disable-bounce.patch
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------------------------------------------------------
From: Vinayak Menon <vinayakm.list@xxxxxxxxx>
Subject: mmKconfig: add an option to disable bounce
There are times when HIGHMEM is enabled, but we don't prefer CONFIG_BOUNCE
to be enabled. CONFIG_BOUNCE can reduce the block device throughput, and
this is not ideal for machines where we don't gain much by enabling it.
So provide an option to deselect CONFIG_BOUNCE. The observation was made
while measuring eMMC throughput using iozone on an ARM device with 1GB
RAM.
Signed-off-by: Vinayak Menon <vinayakm.list@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/Kconfig | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff -puN mm/Kconfig~mm-add-an-option-to-disable-bounce mm/Kconfig
--- a/mm/Kconfig~mm-add-an-option-to-disable-bounce
+++ a/mm/Kconfig
@@ -263,8 +263,14 @@ config ZONE_DMA_FLAG
default "1"
config BOUNCE
- def_bool y
+ bool "Enable bounce buffers"
+ default y
depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
+ help
+ Enable bounce buffers for devices that cannot access
+ the full range of memory available to the CPU. Enabled
+ by default when ZONE_DMA or HIGHMEM is selected, but you
+ may say n to override this.
# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often
# have more than 4GB of memory, but we don't currently use the IOTLB to present
_
Patches currently in -mm which might be from vinayakm.list@xxxxxxxxx are
mmkconfig-add-an-option-to-disable-bounce.patch
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