From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933095Ab0E1RoJ (ORCPT ); Fri, 28 May 2010 13:44:09 -0400 Received: from rcsinet10.oracle.com ([148.87.113.121]:37607 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932842Ab0E1RoE (ORCPT ); Fri, 28 May 2010 13:44:04 -0400 Date: Fri, 28 May 2010 10:41:41 -0700 From: Dan Magenheimer To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, jeremy@goop.org, hugh.dickins@tiscali.co.uk, ngupta@vflare.org, JBeulich@novell.com, chris.mason@oracle.com, kurt.hackel@oracle.com, dave.mccracken@oracle.com, npiggin@suse.de, akpm@linux-foundation.org, riel@redhat.com, avi@redhat.com, pavel@ucw.cz, konrad.wilk@oracle.com, dan.magenheimer@oracle.com Subject: [PATCH V2 4/4] Frontswap (was Transcendent Memory): config files Message-ID: <20100528174141.GA28278@ca-server1.us.oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.16 (2007-06-11) X-Auth-Type: Internal IP X-Source-IP: acsinet15.oracle.com [141.146.126.227] X-CT-RefId: str=0001.0A090204.4C0000AB.006F:SCFMA922111,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [PATCH V2 4/4] Frontswap (was Transcendent Memory): config files Frontswap config defaults to on as the hooks devolve to pointer-compare-to-NULL if no frontswap backend is provided. Signed-off-by: Dan Magenheimer Diffstat: Kconfig | 16 ++++++++++++++++ Makefile | 1 + 2 files changed, 17 insertions(+) --- linux-2.6.34/mm/Makefile 2010-05-16 15:17:36.000000000 -0600 +++ linux-2.6.34-frontswap/mm/Makefile 2010-05-21 12:59:10.000000000 -0600 @@ -17,6 +17,7 @@ obj-y += init-mm.o obj-$(CONFIG_BOUNCE) += bounce.o obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o thrash.o +obj-$(CONFIG_FRONTSWAP) += frontswap.o obj-$(CONFIG_HAS_DMA) += dmapool.o obj-$(CONFIG_HUGETLBFS) += hugetlb.o obj-$(CONFIG_NUMA) += mempolicy.o --- linux-2.6.34/mm/Kconfig 2010-05-16 15:17:36.000000000 -0600 +++ linux-2.6.34-frontswap/mm/Kconfig 2010-05-21 12:59:10.000000000 -0600 @@ -287,3 +287,19 @@ config NOMMU_INITIAL_TRIM_EXCESS of 1 says that all excess pages should be trimmed. See Documentation/nommu-mmap.txt for more information. + +config FRONTSWAP + bool "Enable frontswap pseudo-RAM driver to cache swap pages" + default y + help + Frontswap is so named because it can be thought of as the opposite of + a "backing" store for a swap device. The storage is assumed to be + a synchronous concurrency-safe page-oriented pseudo-RAM device (such + as Xen's Transcendent Memory, aka "tmem") which is not directly + accessible or addressable by the kernel and is of unknown (and + possibly time-varying) size. When a pseudo-RAM device is available, + a signficant swap I/O reduction may be achieved. When none is + available, all frontswap calls are reduced to a single pointer- + compare-against-NULL resulting in a negligible performance hit. + + If unsure, say Y to enable frontswap.