Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754257Ab3DVQ6g (ORCPT ); Mon, 22 Apr 2013 12:58:36 -0400 Received: from casper.infradead.org ([85.118.1.10]:36729 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753870Ab3DVQ6f (ORCPT ); Mon, 22 Apr 2013 12:58:35 -0400 Message-ID: <51756C24.8060505@infradead.org> Date: Mon, 22 Apr 2013 09:58:12 -0700 From: Randy Dunlap User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: vinayakm.list@gmail.com CC: linux-mm@kvack.org, akpm@linux-foundation.org, rientjes@google.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: add an option to disable bounce References: <1366644180-6140-1-git-send-email-vinayakm.list@gmail.com> In-Reply-To: <1366644180-6140-1-git-send-email-vinayakm.list@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1603 Lines: 49 On 04/22/13 08:23, vinayakm.list@gmail.com wrote: > 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 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/