From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx194.postini.com [74.125.245.194]) by kanga.kvack.org (Postfix) with SMTP id 4A48E6B0034 for ; Mon, 22 Apr 2013 11:23:53 -0400 (EDT) Received: by mail-pd0-f173.google.com with SMTP id v10so847034pde.18 for ; Mon, 22 Apr 2013 08:23:52 -0700 (PDT) From: vinayakm.list@gmail.com Subject: [PATCH] mm: add an option to disable bounce Date: Mon, 22 Apr 2013 20:53:00 +0530 Message-Id: <1366644180-6140-1-git-send-email-vinayakm.list@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: akpm@linux-foundation.org, rientjes@google.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Vinayak Menon From: Vinayak Menon 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 --- 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 + 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 -- 1.7.10.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org