From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx166.postini.com [74.125.245.166]) by kanga.kvack.org (Postfix) with SMTP id 5B3256B0033 for ; Wed, 14 Aug 2013 17:23:12 -0400 (EDT) Message-ID: <520BF53D.4020304@tilera.com> Date: Wed, 14 Aug 2013 17:23:09 -0400 From: Chris Metcalf MIME-Version: 1.0 Subject: Re: [PATCH v8] mm: make lru_add_drain_all() selective References: <20130814200748.GI28628@htj.dyndns.org> <201308142029.r7EKTMRw023404@farm-0002.internal.tilera.com> <20130814141258.6289d9926944245befffa3af@linux-foundation.org> In-Reply-To: <20130814141258.6289d9926944245befffa3af@linux-foundation.org> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Tejun Heo , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Thomas Gleixner , Frederic Weisbecker , Cody P Schafer On 8/14/2013 5:12 PM, Andrew Morton wrote: > 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. Thanks. More motivational text is always a good thing. -- Chris Metcalf, Tilera Corp. http://www.tilera.com -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933322Ab3HNVXN (ORCPT ); Wed, 14 Aug 2013 17:23:13 -0400 Received: from usmamail.tilera.com ([12.216.194.151]:18466 "EHLO USMAMAIL.TILERA.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933203Ab3HNVXM (ORCPT ); Wed, 14 Aug 2013 17:23:12 -0400 Message-ID: <520BF53D.4020304@tilera.com> Date: Wed, 14 Aug 2013 17:23:09 -0400 From: Chris Metcalf User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: Andrew Morton CC: Tejun Heo , , , Thomas Gleixner , Frederic Weisbecker , Cody P Schafer Subject: Re: [PATCH v8] mm: make lru_add_drain_all() selective References: <20130814200748.GI28628@htj.dyndns.org> <201308142029.r7EKTMRw023404@farm-0002.internal.tilera.com> <20130814141258.6289d9926944245befffa3af@linux-foundation.org> In-Reply-To: <20130814141258.6289d9926944245befffa3af@linux-foundation.org> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/14/2013 5:12 PM, Andrew Morton wrote: > 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. Thanks. More motivational text is always a good thing. -- Chris Metcalf, Tilera Corp. http://www.tilera.com