From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f51.google.com (mail-ee0-f51.google.com [74.125.83.51]) by kanga.kvack.org (Postfix) with ESMTP id 62F1A6B0035 for ; Thu, 9 Jan 2014 15:01:23 -0500 (EST) Received: by mail-ee0-f51.google.com with SMTP id b15so1540770eek.24 for ; Thu, 09 Jan 2014 12:01:22 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTP id n47si5486197eef.94.2014.01.09.12.01.22 for ; Thu, 09 Jan 2014 12:01:22 -0800 (PST) Message-ID: <52CEFFF3.9010709@redhat.com> Date: Thu, 09 Jan 2014 15:00:51 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH 5/5] mm: x86: Revisit tlb_flushall_shift tuning for page flushes except on IvyBridge References: <1389278098-27154-1-git-send-email-mgorman@suse.de> <1389278098-27154-6-git-send-email-mgorman@suse.de> In-Reply-To: <1389278098-27154-6-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman , Alex Shi , Ingo Molnar Cc: Linus Torvalds , Thomas Gleixner , Andrew Morton , Fengguang Wu , H Peter Anvin , Linux-X86 , Linux-MM , LKML On 01/09/2014 09:34 AM, Mel Gorman wrote: > There was a large ebizzy performance regression that was bisected to commit > 611ae8e3 (x86/tlb: enable tlb flush range support for x86). The problem > was related to the tlb_flushall_shift tuning for IvyBridge which was > altered. The problem is that it is not clear if the tuning values for each > CPU family is correct as the methodology used to tune the values is unclear. > > This patch uses a conservative tlb_flushall_shift value for all CPU families > except IvyBridge so the decision can be revisited if any regression is found > as a result of this change. IvyBridge is an exception as testing with one > methodology determined that the value of 2 is acceptable. Details are in the > changelog for the patch "x86: mm: Change tlb_flushall_shift for IvyBridge". > > One important aspect of this to watch out for is Xen. The original commit > log mentioned large performance gains on Xen. It's possible Xen is more > sensitive to this value if it flushes small ranges of pages more frequently > than workloads on bare metal typically do. > > Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel -- 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 S1757295AbaAIUC2 (ORCPT ); Thu, 9 Jan 2014 15:02:28 -0500 Received: from mx1.redhat.com ([209.132.183.28]:55369 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756062AbaAIUCZ (ORCPT ); Thu, 9 Jan 2014 15:02:25 -0500 Message-ID: <52CEFFF3.9010709@redhat.com> Date: Thu, 09 Jan 2014 15:00:51 -0500 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Mel Gorman , Alex Shi , Ingo Molnar CC: Linus Torvalds , Thomas Gleixner , Andrew Morton , Fengguang Wu , H Peter Anvin , Linux-X86 , Linux-MM , LKML Subject: Re: [PATCH 5/5] mm: x86: Revisit tlb_flushall_shift tuning for page flushes except on IvyBridge References: <1389278098-27154-1-git-send-email-mgorman@suse.de> <1389278098-27154-6-git-send-email-mgorman@suse.de> In-Reply-To: <1389278098-27154-6-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/09/2014 09:34 AM, Mel Gorman wrote: > There was a large ebizzy performance regression that was bisected to commit > 611ae8e3 (x86/tlb: enable tlb flush range support for x86). The problem > was related to the tlb_flushall_shift tuning for IvyBridge which was > altered. The problem is that it is not clear if the tuning values for each > CPU family is correct as the methodology used to tune the values is unclear. > > This patch uses a conservative tlb_flushall_shift value for all CPU families > except IvyBridge so the decision can be revisited if any regression is found > as a result of this change. IvyBridge is an exception as testing with one > methodology determined that the value of 2 is acceptable. Details are in the > changelog for the patch "x86: mm: Change tlb_flushall_shift for IvyBridge". > > One important aspect of this to watch out for is Xen. The original commit > log mentioned large performance gains on Xen. It's possible Xen is more > sensitive to this value if it flushes small ranges of pages more frequently > than workloads on bare metal typically do. > > Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel