Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752148AbdHRQz6 (ORCPT ); Fri, 18 Aug 2017 12:55:58 -0400 Received: from mail-oi0-f67.google.com ([209.85.218.67]:36920 "EHLO mail-oi0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751052AbdHRQz5 (ORCPT ); Fri, 18 Aug 2017 12:55:57 -0400 MIME-Version: 1.0 In-Reply-To: <20170818122339.24grcbzyhnzmr4qw@techsingularity.net> References: <84c7f26182b7f4723c0fe3b34ba912a9de92b8b7.1502758114.git.tim.c.chen@linux.intel.com> <37D7C6CF3E00A74B8858931C1DB2F07753786CE9@SHSMSX103.ccr.corp.intel.com> <37D7C6CF3E00A74B8858931C1DB2F0775378761B@SHSMSX103.ccr.corp.intel.com> <20170818122339.24grcbzyhnzmr4qw@techsingularity.net> From: Linus Torvalds Date: Fri, 18 Aug 2017 09:55:56 -0700 X-Google-Sender-Auth: ib1BmuVXv-meVgS6n31zlfeWbcI Message-ID: Subject: Re: [PATCH 1/2] sched/wait: Break up long wake list walk To: Mel Gorman Cc: "Liang, Kan" , Mel Gorman , "Kirill A. Shutemov" , Tim Chen , Peter Zijlstra , Ingo Molnar , Andi Kleen , Andrew Morton , Johannes Weiner , Jan Kara , linux-mm , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 877 Lines: 23 On Fri, Aug 18, 2017 at 5:23 AM, Mel Gorman wrote: > > new_page = alloc_pages_node(node, > - (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE), > + (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE) & ~__GFP_DIRECT_RECLAIM, > HPAGE_PMD_ORDER); That can't make any difference. We already have: #define GFP_TRANSHUGE_LIGHT ((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \ __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM) and that "& ~__GFP_RECLAIM" is removing __GFP_DIRECT_RECLAIM. So that patch is a no-op, afaik. Is there something else expensive in there? It *might* be simply that we have a shit-ton of threads, and the thread that holds the page lock for migration is just preempted out. even if it doesn't really do anything particularly expensive. Linus