From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751334AbdBWTJN (ORCPT ); Thu, 23 Feb 2017 14:09:13 -0500 Received: from gum.cmpxchg.org ([85.214.110.215]:36914 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751099AbdBWTJL (ORCPT ); Thu, 23 Feb 2017 14:09:11 -0500 Date: Thu, 23 Feb 2017 14:03:13 -0500 From: Johannes Weiner To: Michal Hocko Cc: Laurent Dufour , Vladimir Davydov , Balbir Singh , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] mm/cgroup: delay soft limit data allocation Message-ID: <20170223190313.GB6088@cmpxchg.org> References: <1487856999-16581-1-git-send-email-ldufour@linux.vnet.ibm.com> <1487856999-16581-3-git-send-email-ldufour@linux.vnet.ibm.com> <20170223153107.GD29056@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170223153107.GD29056@dhcp22.suse.cz> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 23, 2017 at 04:31:07PM +0100, Michal Hocko wrote: > On Thu 23-02-17 14:36:39, Laurent Dufour wrote: > > Until a soft limit is set to a cgroup, the soft limit data are useless > > so delay this allocation when a limit is set. > > Hmm, I am still undecided whether this is actually worth it. On one hand > distribution kernels tend to have quite large NUMA_SHIFT (e.g. SLES has > NUMA_SHIFT=10 and then we will save 8kB+12kB which is not hell of a lot > but always good if we can save that, especially for a rarely used > feature. The code grown on the other hand (it was in __init section > previously) which is a minus, on the other hand. > > What do you think Johannes? Hohumm, saving 5 pages on a NUMA machine vs. the additional complexity and the increased risk of memory problems when somebody sets up a soft limit after some uptime... I don't think I can give a strong yes or no on this one, so inertia wins for me; I'd just leave it alone. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Weiner Subject: Re: [PATCH v2 2/2] mm/cgroup: delay soft limit data allocation Date: Thu, 23 Feb 2017 14:03:13 -0500 Message-ID: <20170223190313.GB6088@cmpxchg.org> References: <1487856999-16581-1-git-send-email-ldufour@linux.vnet.ibm.com> <1487856999-16581-3-git-send-email-ldufour@linux.vnet.ibm.com> <20170223153107.GD29056@dhcp22.suse.cz> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=cmpxchg.org ; s=x; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject: Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=LfqzPD4Fwee/0dPxRYunaaYpLCTefiRNbqL4x1obO1Y=; b=P/13gaHIuMzi/mE/vGvc050YDY 7z5+kAVKc7SMj4imIsfrbvehyr5k2H3iJ2fYrI3kq7nNAodFrKbKR/w9/ym527Psv89fKGmIo2qll EM0/5rXVZKFBoxBb1wQ3LIIA6sWLDeZp3OZnRk/WNoPwfTRYJukm/TpUFmuAG8a8PB+4=; Content-Disposition: inline In-Reply-To: <20170223153107.GD29056@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Michal Hocko Cc: Laurent Dufour , Vladimir Davydov , Balbir Singh , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, Feb 23, 2017 at 04:31:07PM +0100, Michal Hocko wrote: > On Thu 23-02-17 14:36:39, Laurent Dufour wrote: > > Until a soft limit is set to a cgroup, the soft limit data are useless > > so delay this allocation when a limit is set. > > Hmm, I am still undecided whether this is actually worth it. On one hand > distribution kernels tend to have quite large NUMA_SHIFT (e.g. SLES has > NUMA_SHIFT=10 and then we will save 8kB+12kB which is not hell of a lot > but always good if we can save that, especially for a rarely used > feature. The code grown on the other hand (it was in __init section > previously) which is a minus, on the other hand. > > What do you think Johannes? Hohumm, saving 5 pages on a NUMA machine vs. the additional complexity and the increased risk of memory problems when somebody sets up a soft limit after some uptime... I don't think I can give a strong yes or no on this one, so inertia wins for me; I'd just leave it alone. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org