On 04/22/13 08:23, vinayakm.l...@gmail.com wrote:
> From: Vinayak Menon <vinayakm.l...@gmail.com>
>
> 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.l...@gmail.com>
> ---
> mm/Kconfig | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 3bea74f..29f9736 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -263,8 +263,14 @@ config ZONE_DMA_FLAG
> default "1"
>
> config BOUNCE
> + bool "Enable bounce buffers"
> def_bool 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 HIGMEM is selected, but you
HIGHMEM
> + 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
>
--
~Randy
--
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