On Monday 22 April 2013 10:28 PM, Randy Dunlap wrote: > On 04/22/13 08:23, vinayakm.list@xxxxxxxxx wrote: >> From: Vinayak Menon <vinayakm.list@xxxxxxxxx> >> >> 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> >> --- >> 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 >> > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>