From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 2/2] cgroup: add xattr support Date: Wed, 18 Jan 2012 18:40:21 -0800 Message-ID: <20120119024021.GI21533@google.com> References: <4F13DA90.2000603@cn.fujitsu.com> <4F13DAA9.4070703@cn.fujitsu.com> <20120117175322.GC6762@google.com> <20120118213638.GA21533@google.com> <20120119014727.GG29242@tango.0pointer.de> <20120119022005.GG21533@google.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=wfnZ2AkvdkU9xoLDsIjLUEBL6atKAX+zne8qypVei2c=; b=bmsQ9eWBaw3RYdPErZGmOv8nK7+7iOm3nAAadzrhwoB6nP/cHukqst85jC/6tYDKNO 3AgwWy3Nkr4hTnkCAouu3pP0qA7VpMeEuxXWrJTaxE1Cn2y8Spazztc4myS8vwPtVr6N W+vhIyFJMuajVMv+vYr554fxVqkuBW1kqaoUo= Content-Disposition: inline In-Reply-To: <20120119022005.GG21533-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Lennart Poettering Cc: Kay Sievers , Li Zefan , LKML , Cgroups On Wed, Jan 18, 2012 at 06:20:05PM -0800, Tejun Heo wrote: > Hello, Lennart, Li. > > Two things. > > * Probably I'm missing something but isn't the systemd cgroup > hierarchy already managed by systemd? If so, I don't see how > managing tmpfs on the side would noticeably make things more > fragile. It would take a bit more care after, for example, restart > but it shouldn't be too complex, no? > > * FS attributes already being used for userland information seems like > a good argument, but we shouldn't add separate specialized xattr > implementation to different pseudo filesystems. For it to be > acceptable, it should be a libfs thing easily applicable to any > pseudo FS and definitely shouldn't be using kmem for storage. Also note that tmpfs also implies size limit. We definitely need some form of control over the amount of memory xattr may consume. Thanks. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755649Ab2ASCk1 (ORCPT ); Wed, 18 Jan 2012 21:40:27 -0500 Received: from mail-iy0-f174.google.com ([209.85.210.174]:48290 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753208Ab2ASCkZ (ORCPT ); Wed, 18 Jan 2012 21:40:25 -0500 Date: Wed, 18 Jan 2012 18:40:21 -0800 From: Tejun Heo To: Lennart Poettering Cc: Kay Sievers , Li Zefan , LKML , Cgroups Subject: Re: [PATCH 2/2] cgroup: add xattr support Message-ID: <20120119024021.GI21533@google.com> References: <4F13DA90.2000603@cn.fujitsu.com> <4F13DAA9.4070703@cn.fujitsu.com> <20120117175322.GC6762@google.com> <20120118213638.GA21533@google.com> <20120119014727.GG29242@tango.0pointer.de> <20120119022005.GG21533@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120119022005.GG21533@google.com> 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 On Wed, Jan 18, 2012 at 06:20:05PM -0800, Tejun Heo wrote: > Hello, Lennart, Li. > > Two things. > > * Probably I'm missing something but isn't the systemd cgroup > hierarchy already managed by systemd? If so, I don't see how > managing tmpfs on the side would noticeably make things more > fragile. It would take a bit more care after, for example, restart > but it shouldn't be too complex, no? > > * FS attributes already being used for userland information seems like > a good argument, but we shouldn't add separate specialized xattr > implementation to different pseudo filesystems. For it to be > acceptable, it should be a libfs thing easily applicable to any > pseudo FS and definitely shouldn't be using kmem for storage. Also note that tmpfs also implies size limit. We definitely need some form of control over the amount of memory xattr may consume. Thanks. -- tejun