Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760233Ab3HNVNA (ORCPT ); Wed, 14 Aug 2013 17:13:00 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55281 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760012Ab3HNVM7 (ORCPT ); Wed, 14 Aug 2013 17:12:59 -0400 Date: Wed, 14 Aug 2013 14:12:58 -0700 From: Andrew Morton To: Chris Metcalf Cc: Tejun Heo , , , Thomas Gleixner , Frederic Weisbecker , Cody P Schafer Subject: Re: [PATCH v8] mm: make lru_add_drain_all() selective Message-Id: <20130814141258.6289d9926944245befffa3af@linux-foundation.org> In-Reply-To: <201308142029.r7EKTMRw023404@farm-0002.internal.tilera.com> References: <20130814200748.GI28628@htj.dyndns.org> <201308142029.r7EKTMRw023404@farm-0002.internal.tilera.com> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 940 Lines: 21 On Wed, 14 Aug 2013 16:22:18 -0400 Chris Metcalf wrote: > This change makes lru_add_drain_all() only selectively interrupt > the cpus that have per-cpu free pages that can be drained. > > This is important in nohz mode where calling mlockall(), for > example, otherwise will interrupt every core unnecessarily. Changelog isn't very informative. I added this: : This is important on workloads where nohz cores are handling 10 Gb traffic : in userspace. Those CPUs do not enter the kernel and place pages into LRU : pagevecs and they really, really don't want to be interrupted, or they : drop packets on the floor. to attempt to describe the rationale for the patch. -- 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/