Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755964Ab0KLIbI (ORCPT ); Fri, 12 Nov 2010 03:31:08 -0500 Received: from cantor2.suse.de ([195.135.220.15]:42650 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752052Ab0KLIbH (ORCPT ); Fri, 12 Nov 2010 03:31:07 -0500 Date: Fri, 12 Nov 2010 09:31:03 +0100 From: Michal Hocko To: Daisuke Nishimura Cc: linux-mm@kvack.org, KAMEZAWA Hiroyuki , linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] Make swap accounting default behavior configurable v2 Message-ID: <20101112083103.GB7285@tiehlicka.suse.cz> References: <20101110125154.GC5867@tiehlicka.suse.cz> <20101111094613.eab2ec0b.nishimura@mxp.nes.nec.co.jp> <20101111093155.GA20630@tiehlicka.suse.cz> <20101112094118.b02b669f.nishimura@mxp.nes.nec.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101112094118.b02b669f.nishimura@mxp.nes.nec.co.jp> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6895 Lines: 167 On Fri 12-11-10 09:41:18, Daisuke Nishimura wrote: > On Thu, 11 Nov 2010 10:31:55 +0100 > Michal Hocko wrote: > > > On Thu 11-11-10 09:46:13, Daisuke Nishimura wrote: > > > On Wed, 10 Nov 2010 13:51:54 +0100 > > > Michal Hocko wrote: > > > > > > > Hi, > > > > could you consider the patch bellow? It basically changes the default > > > > swap accounting behavior (when it is turned on in configuration) to be > > > > configurable as well. > > > > > > > > The rationale is described in the patch but in short it makes it much > > > > more easier to enable this feature in distribution kernels as the > > > > functionality can be provided in the general purpose kernel (with the > > > > option disabled) without any drawbacks and interested users can enable > > > > it. This is not possible currently. > > > > > > > > I am aware that boot command line parameter name change is not ideal but > > > > the original semantic wasn't good enough and I don't like > > > > noswapaccount=yes|no very much. > > > > > > > > If we really have to stick to it I can rework the patch to keep the name > > > > and just add the yes|no logic, though. Or we can keep the original one > > > > and add swapaccount paramete which would mean the oposite as the other > > > > one. > > > > > > > hmm, I agree that current parameter name(noswapaccount) is not desirable > > > for yes|no, but IMHO changing the user interface(iow, making what worked before > > > unusable) is worse. > > > > > > Although I'm not sure how many people are using this parameter, I vote for > > > using "noswapaccount[=(yes|no)]". > > > > Isn't a new swapaccount parameter better than that? I know we don't want > > to have too many parameters but having a something with a clear meaning > > is better IMO (noswapaccount=no doesn't sound very intuitive to me). > > > Fair enough. It's just an trade-off between compatibility and understandability. > > > > And you should update Documentation/kernel-parameters.txt too. > > > > Yes, I am aware of that and will do that once there is an agreement on > > the patch itself. At this stage, I just wanted to have a feadback about > > the change. > > > I'll ack your patch when it's been released with documentation update. Changes since v1: * do not remove noswapaccount parameter and add swapaccount parameter instead * Documentation/kernel-parameters.txt updated --- >From c60e3d76702cd9b4b5b13c01be335da31d03bc1c Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Wed, 10 Nov 2010 13:30:04 +0100 Subject: [PATCH] Make swap accounting default behavior configurable Swap accounting can be configured by CONFIG_CGROUP_MEM_RES_CTLR_SWAP configuration option and then it is turned on by default. There is a boot option (noswapaccount) which can disable this feature. This makes it hard for distributors to enable the configuration option as this feature leads to a bigger memory consumption and this is a no-go for general purpose distribution kernel. On the other hand swap accounting may be very usuful for some workloads. This patch adds a new configuration option which controls the default behavior (CGROUP_MEM_RES_CTLR_SWAP_ENABLED). If the option is selected then the feature is turned on by default. It also adds a new boot parameter swapaccount which (contrary to noswapaccount) enables the feature. (I would consider swapaccount=yes|no semantic with removed noswapaccount parameter much better but this parameter is kind of API which might be in use and unexpected breakage is no-go.) The default behavior is unchanged (if CONFIG_CGROUP_MEM_RES_CTLR_SWAP is enabled then CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED is enabled as well) Signed-off-by: Michal Hocko --- Documentation/kernel-parameters.txt | 2 ++ init/Kconfig | 13 +++++++++++++ mm/memcontrol.c | 15 ++++++++++++++- 3 files changed, 29 insertions(+), 1 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index ed45e98..7077148 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1752,6 +1752,8 @@ and is between 256 and 4096 characters. It is defined in the file noswapaccount [KNL] Disable accounting of swap in memory resource controller. (See Documentation/cgroups/memory.txt) + swapaccount [KNL] Enable accounting of swap in memory resource + controller. (See Documentation/cgroups/memory.txt) nosync [HW,M68K] Disables sync negotiation for all devices. diff --git a/init/Kconfig b/init/Kconfig index 88c1046..c972899 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -613,6 +613,19 @@ config CGROUP_MEM_RES_CTLR_SWAP if boot option "noswapaccount" is set, swap will not be accounted. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page size is 4096bytes, 512k per 1Gbytes of swap. +config CGROUP_MEM_RES_CTLR_SWAP_ENABLED + bool "Memory Resource Controller Swap Extension enabled by default" + depends on CGROUP_MEM_RES_CTLR_SWAP + default y + help + Memory Resource Controller Swap Extension comes with its price in + a bigger memory consumption. General purpose distribution kernels + which want to enable the feautre but keep it disabled by default + and let the user enable it by swapaccount boot command line + parameter should have this option unselected. + For those who want to have the feature enabled by default should + select this option (if, for some reason, they need to disable it + then noswapaccount does the trick). menuconfig CGROUP_SCHED bool "Group CPU scheduler" diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 9a99cfa..4f479fe 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -61,7 +61,14 @@ struct mem_cgroup *root_mem_cgroup __read_mostly; #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP /* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */ int do_swap_account __read_mostly; -static int really_do_swap_account __initdata = 1; /* for remember boot option*/ + +/* for remember boot option*/ +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED +static int really_do_swap_account __initdata = 1; +#else +static int really_do_swap_account __initdata = 0; +#endif + #else #define do_swap_account (0) #endif @@ -4909,6 +4916,12 @@ struct cgroup_subsys mem_cgroup_subsys = { }; #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP +static int __init enable_swap_account(char *s) +{ + really_do_swap_account = 1; + return 1; +} +__setup("swapaccount", enable_swap_account); static int __init disable_swap_account(char *s) { -- 1.7.2.3 -- 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/