path: root/mm
diff options
authorVinayak Menon <vinayakm.list@gmail.com>2013-04-29 15:08:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-29 15:54:40 -0700
commit9ca24e2e19325edc3ed0b437657d26219b7a768a (patch)
treef77c807f879d8a23ababae31a9006a204d0a204a /mm
parentb476e2951fcf7a25574b7b193944b041687f3ed4 (diff)
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@gmail.com> Cc: David Rientjes <rientjes@google.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 7 insertions, 1 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index 3bea74f1ccf..e742d06285b 100644
--- a/mm/Kconfig
+++ b/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