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SubjectRe: [PATCH] mm: add an option to disable bounce
On Monday 22 April 2013 10:28 PM, Randy Dunlap wrote:

> On 04/22/13 08:23, vinayakm.list@gmail.com wrote:
>> From: Vinayak Menon <vinayakm.list@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.list@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


Thanks. I will correct this.

>
>> + 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
>>
>
>




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