From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f178.google.com (mail-ig0-f178.google.com [209.85.213.178]) by kanga.kvack.org (Postfix) with ESMTP id D85736B0038 for ; Mon, 27 Apr 2015 16:07:46 -0400 (EDT) Received: by igbhj9 with SMTP id hj9so3448372igb.1 for ; Mon, 27 Apr 2015 13:07:46 -0700 (PDT) Received: from g1t5425.austin.hp.com (g1t5425.austin.hp.com. [15.216.225.55]) by mx.google.com with ESMTPS id e38si16511359ioj.105.2015.04.27.13.07.46 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Apr 2015 13:07:46 -0700 (PDT) Message-ID: <553E970E.2040406@hp.com> Date: Mon, 27 Apr 2015 16:07:42 -0400 From: Waiman Long MIME-Version: 1.0 Subject: Re: [PATCH 10/13] x86: mm: Enable deferred struct page initialisation on x86-64 References: <1429722473-28118-1-git-send-email-mgorman@suse.de> <1429722473-28118-11-git-send-email-mgorman@suse.de> <20150422164500.121a355e6b578243cb3650e3@linux-foundation.org> <20150423092327.GJ14842@suse.de> <553A54C5.3060106@hp.com> <20150424152007.GD2449@suse.de> <553A93BB.1010404@hp.com> <20150425172859.GE2449@suse.de> In-Reply-To: <20150425172859.GE2449@suse.de> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Andrew Morton , Linux-MM , Nathan Zimmer , Dave Hansen , Scott Norton , Daniel J Blueman , LKML On 04/25/2015 01:28 PM, Mel Gorman wrote: > On Fri, Apr 24, 2015 at 03:04:27PM -0400, Waiman Long wrote: >>>> Within a NUMA node, however, we can split the >>>> memory initialization to 2 or more local CPUs if the memory size is >>>> big enough. >>>> >>> I considered it but discarded the idea. It'd be more complex to setup and >>> the two CPUs could simply end up contending on the same memory bus as >>> well as contending on zone->lock. >>> >> I don't think we need that now. However, we may have to consider >> this when one day even a single node can have TBs of memory unless >> we move to a page size larger than 4k. >> > We'll cross that bridge when we come to it. I suspect there is more room > for improvement in the initialisation that would be worth trying before > resorting to more threads. With more threads there is a risk that we hit > memory bus contention and a high risk that it actually is worse due to > contending on zone->lock when freeing the pages. > > In the meantime, do you mind updating the before/after figures for your > test machine with this series please? > I will test the latest patch once I got my hand on a 12TB machine. Cheers, Longman -- 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