From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id C33B36B0069 for ; Tue, 17 Jan 2017 14:16:58 -0500 (EST) Received: by mail-pg0-f69.google.com with SMTP id t6so114947288pgt.6 for ; Tue, 17 Jan 2017 11:16:58 -0800 (PST) Received: from foss.arm.com (foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id r82si25821300pfl.199.2017.01.17.11.16.57 for ; Tue, 17 Jan 2017 11:16:57 -0800 (PST) Date: Tue, 17 Jan 2017 19:16:56 +0000 From: Will Deacon Subject: Re: [PATCH v3] arm64: mm: Fix NOMAP page initialization Message-ID: <20170117191656.GS27328@arm.com> References: <20170109115320.GI4930@rric.localdomain> <20170112160535.GF13843@arm.com> <20170112185825.GE5020@rric.localdomain> <20170113091903.GA22538@arm.com> <20170113131500.GS4930@rric.localdomain> <20170117100015.GG5020@rric.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170117100015.GG5020@rric.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Robert Richter Cc: Ard Biesheuvel , Hanjun Guo , Russell King , Catalin Marinas , David Daney , Mark Rutland , James Morse , Yisheng Xie , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" On Tue, Jan 17, 2017 at 11:00:15AM +0100, Robert Richter wrote: > On 13.01.17 14:15:00, Robert Richter wrote: > > On 13.01.17 09:19:04, Will Deacon wrote: > > > On Thu, Jan 12, 2017 at 07:58:25PM +0100, Robert Richter wrote: > > > > On 12.01.17 16:05:36, Will Deacon wrote: > > > > > On Mon, Jan 09, 2017 at 12:53:20PM +0100, Robert Richter wrote: > > > > > > > > > > Kernel compile times (3 runs each): > > > > > > > > > > > > pfn_valid_within(): > > > > > > > > > > > > real 6m4.088s > > > > > > user 372m57.607s > > > > > > sys 16m55.158s > > > > > > > > > > > > real 6m1.532s > > > > > > user 372m48.453s > > > > > > sys 16m50.370s > > > > > > > > > > > > real 6m4.061s > > > > > > user 373m18.753s > > > > > > sys 16m57.027s > > > > > > > > > > Did you reboot the machine between each build here, or only when changing > > > > > kernel? If the latter, do you see variations in kernel build time by simply > > > > > rebooting the same Image? > > > > > > > > I built it in a loop on the shell, so no reboots between builds. Note > > > > that I was building the kernel in /dev/shm to not access harddisks. I > > > > think build times should be comparable then since there is no fs > > > > caching. > > > > > > I guess I'm really asking what the standard deviation is if you *do* reboot > > > between builds, using the same kernel. It's hard to tell whether the numbers > > > are due to the patches, or just because of noise incurred by the way things > > > happen to initialise. > > > > Ok, I am going to test this. > > See below the data for a test with reboots between every 3 builds (9 > builds per kernel). Though some deviation can be seen between reboots > there is a trend. I can't really see the trend given that, for system time, your pfn_valid_within results have a variance of ~9 and the early_pfn_valid results have a variance of ~92. Given that the variance seems to come about due to the reboots, I think we need more numbers to establish whether the data sets end up largely overlapping or if they really are disjoint. Will -- 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