Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423138Ab2JaPI1 (ORCPT ); Wed, 31 Oct 2012 11:08:27 -0400 Received: from acsinet15.oracle.com ([141.146.126.227]:39599 "EHLO acsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423027Ab2JaPIX (ORCPT ); Wed, 31 Oct 2012 11:08:23 -0400 From: Dan Magenheimer To: devel@linuxdriverproject.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, linux-mm@kvack.org, ngupta@vflare.org, konrad.wilk@oracle.com, sjenning@linux.vnet.ibm.com, minchan@kernel.org, dan.magenheimer@oracle.com, fschmaus@gmail.com, andor.damm@googlemail.com, ilendir@googlemail.com, akpm@linux-foundation.org, mgorman@suse.de Subject: [PATCH 0/5] enable all tmem backends to be built and loaded as modules Date: Wed, 31 Oct 2012 08:07:49 -0700 Message-Id: <1351696074-29362-1-git-send-email-dan.magenheimer@oracle.com> X-Mailer: git-send-email 1.7.5.1 X-Source-IP: ucsinet22.oracle.com [156.151.31.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4644 Lines: 89 Since various parts of transcendent memory ("tmem") [1] were first posted in 2009, reviewers have suggested that various tmem features should be built as a module and enabled by loading the module, rather than the current clunky method of compiling as a built-in and enabling via boot parameter. Due to certain tmem initialization steps, that was not feasible at the time. [1] http://lwn.net/Articles/454795/ This patchset allows each of the three merged transcendent memory backends (zcache, ramster, Xen tmem) to be used as modules by first enabling transcendent memory frontends (cleancache, frontswap) to deal with "lazy initialization" and, second, by adding the necessary code for the backends to be built and loaded as modules. The original mechanism to enable tmem backends -- namely to hardwire them into the kernel and select/enable one with a kernel boot parameter -- is retained but should be considered deprecated. When backends are loaded as modules, certain knobs will now be properly selected via module_params rather than via undocumented kernel boot parameters. Note that module UNloading is not yet supported as it is lower priority and will require significant additional work. The lazy initialization support is necessary because filesystems and swap devices are normally mounted early in boot and these activites normally trigger tmem calls to setup certain data structures; if the respective cleancache/frontswap ops are not yet registered by a back end, the tmem setup would fail for these devices and cleancache/frontswap would never be enabled for them which limits much of the value of tmem in many system configurations. Lazy initialization records the necessary information in cleancache/frontswap data structures and "replays" it after the ops are registered to ensure that all filesystems and swap devices can benefit from the loaded tmem backend. Patches 1 and 2 are the original [2] patches to cleancache and frontswap proposed by Erlangen University, but rebased to 3.7-rcN plus a couple of bug fixes I found necessary to run properly. I have not attempted any code cleanup. I have also added defines to ensure at runtime that backends are not loaded as modules if the frontend patches are not yet merged; this is useful to avoid any build dependency (since the frontends may be merged into linux-next through different trees and at different times than some backends) and once the entire patchset is safely merged, these defines/ifdefs can be removed. [2] http://www.spinics.net/lists/linux-mm/msg31490.html Patch 3 enables module support for zcache2. Zsmalloc support has not yet been merged into zcache2 but, once merged, could now easily be selected via a module_param. Patch 4 enables module support for ramster. Ramster will now be enabled with a module_param to zcache2. Patch 5 enables module support for the Xen tmem shim. Xen self-ballooning and frontswap-selfshrinking are also "lazily" initialized when the Xen tmem shim is loaded as a module, unless explicitly disabled by module_params. Signed-off-by: Dan Magenheimer --- Diffstat: drivers/staging/ramster/Kconfig | 6 +- drivers/staging/ramster/Makefile | 11 +- drivers/staging/ramster/ramster.h | 6 +- drivers/staging/ramster/ramster/nodemanager.c | 9 +- drivers/staging/ramster/ramster/ramster.c | 29 +++- drivers/staging/ramster/ramster/ramster.h | 2 +- .../staging/ramster/ramster/ramster_nodemanager.h | 2 + drivers/staging/ramster/tmem.c | 6 +- drivers/staging/ramster/tmem.h | 8 +- drivers/staging/ramster/zcache-main.c | 61 +++++++- drivers/staging/ramster/zcache.h | 2 +- drivers/xen/Kconfig | 4 +- drivers/xen/tmem.c | 56 ++++++-- drivers/xen/xen-selfballoon.c | 13 +- include/linux/cleancache.h | 1 + include/linux/frontswap.h | 1 + include/xen/tmem.h | 8 + mm/cleancache.c | 157 +++++++++++++++++-- mm/frontswap.c | 70 ++++++++- 19 files changed, 379 insertions(+), 73 deletions(-) -- 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/