From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH] fix bad behavior in use_hierarchy file Date: Tue, 26 Jun 2012 10:55:13 -0700 Message-ID: <20120626175513.GO3869@google.com> References: <1340616061-1955-1-git-send-email-glommer@parallels.com> <20120625204908.GL3869@google.com> <20120626075653.GD6713@tiehlicka.suse.cz> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=/RBpGC7Hji/r/XTtx2NbpS8X8V1i9UMiU1AD3AHNJzA=; b=SqDP1uvkw6nhsa/9EDbJbCF7PB48VZnf+xwazmW+HbSMw1KPwFXaIF9VWVxSTmyetL aljBLzCLY8jtRq7ogj04QyxoyHjlkD7vWuEH9TIj2aHQfdN5qz41CR1ll5Vo+qn6udGZ 9Q3xdsKMPLHo8eLl6YJuTjjktv20u9rc40nzGG72VPTuqGe7OY+QgCcOYjqf1T4l7ouj K4xpDbMtAHjXBNmOOlKlm88IOdcTWQb8KHWtMVutuNSf0HKBmd3+n5csq8NdXH6xUe7d JmzNT+xUdGFjLEcdTGwABU1A+bsF06cfhJ4RbmqcPsdc06QlmzJ+QcBDh79uMtqoJA1Y X07Q== Content-Disposition: inline In-Reply-To: <20120626075653.GD6713-VqjxzfR4DlwKmadIfiO5sKVXKuFTiq87@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Michal Hocko Cc: Glauber Costa , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Andrew Morton , devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, Dhaval Giani , Kamezawa Hiroyuki , Johannes Weiner , Ying Han , gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org Hello, On Tue, Jun 26, 2012 at 09:56:53AM +0200, Michal Hocko wrote: > [Adding Ying to CC - they are using hierarchies AFAIU in their workloads] Ooh, I'm they. :) Asking around.... okay, so google does use .use_hierarchy but it's a tree-wide thing and would be perfectly happy with a global switch. > On Mon 25-06-12 13:49:08, Tejun Heo wrote: > [...] > > A bit of delta but is there any chance we can either deprecate > > .use_hierarhcy or at least make it global toggle instead of subtree > > thing? > > So what you are proposing is to have all subtrees of the root either > hierarchical or not, right? Yeap. Just make it a global switch. Probably determined on mount time. > > This seems needlessly complicated. :( > > Toggle wouldn't help much I am afraid. We would still have to > distinguish (non)hierarchical cases. And I am not sure we can make > everything hierarchical easily. I'm kinda confused by this paragraph. What do you mean by "wouldn't help much"? Do you mean in terms of complexity? > Most users (from my experience) ignored use_hierarchy for some reasons > and the end results might be really unexpected for them if they used > deeper subtrees (which might be needed due to combination with other > controller(s)). Oh yeah, we can't change the default behavior like that. The transition should be a lot more gradual. Even if making .use_hierarchy doesn't help much in terms of reducing complexity right now, it would at least allow us to weed out and prevent wacky woo-hoo mom-look-at-what-I-can-do configurations which will be a lot more difficult to deal with for both us and such users (if we end up forcing hierarchy). Thanks. -- tejun