From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f199.google.com (mail-io0-f199.google.com [209.85.223.199]) by kanga.kvack.org (Postfix) with ESMTP id EBC806B0260 for ; Tue, 17 May 2016 21:42:25 -0400 (EDT) Received: by mail-io0-f199.google.com with SMTP id d62so75720082iof.1 for ; Tue, 17 May 2016 18:42:25 -0700 (PDT) Received: from lgeamrelo12.lge.com (LGEAMRELO12.lge.com. [156.147.23.52]) by mx.google.com with ESMTP id a134si17597145itc.56.2016.05.17.18.42.24 for ; Tue, 17 May 2016 18:42:25 -0700 (PDT) Date: Wed, 18 May 2016 10:42:29 +0900 From: Minchan Kim Subject: [PATCH] mm: disable fault around on emulated access bit architecture Message-ID: <20160518014229.GB21538@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Vinayak Menon , linux-mm@kvack.org, linux-kernel@vger.kernel.org, dan.j.williams@intel.com, mgorman@suse.de, vbabka@suse.cz, kirill.shutemov@linux.intel.com, dave.hansen@linux.intel.com, hughd@google.com, linux-arch@vger.kernel.org On Tue, May 17, 2016 at 03:34:23PM +0300, Kirill A. Shutemov wrote: > On Mon, May 16, 2016 at 11:56:32PM +0900, Minchan Kim wrote: > > On Mon, May 16, 2016 at 05:29:00PM +0300, Kirill A. Shutemov wrote: > > > > Kirill, > > > > You wanted to test non-HW access bit system and I did. > > > > What's your opinion? > > > > > > Sorry, for late response. > > > > > > My patch is incomlete: we need to find a way to not mark pte as old if we > > > handle page fault for the address the pte represents. > > > > I'm sure you can handle it but my point is there wouldn't be a big gain > > although you can handle it in non-HW access bit system. Okay, let's be > > more clear because I don't have every non-HW access bit architecture. > > At least, current mobile workload in ARM which I have wouldn't be huge > > benefit. > > I will say one more. > > I tested the workload on quad-core system and core speed is not so slow > > compared to recent other mobile phone SoC. Even when I tested the benchmark > > without pte_mkold, the benefit is within noise because storage is really > > slow so major fault is dominant factor. So, I decide test storage from eMMC > > to eSATA. And then finally, I manage to see the a little beneift with > > fault_around without pte_mkold. > > > > However, let's consider side-effect aspect from fault_around. > > > > 1. Increase slab shrinking compard to old > > 2. high level vmpressure compared to old > > > > With considering that regressions on my system, it's really not worth to > > try at the moment. > > That's why I wanted to disable fault_around as default in non-HW access > > bit system. > > Feel free to post such patch. I guess it's reasonable.