From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 8587A6B0033 for ; Tue, 10 Jan 2017 18:48:46 -0500 (EST) Received: by mail-pf0-f198.google.com with SMTP id 80so140731319pfy.2 for ; Tue, 10 Jan 2017 15:48:46 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id u22si3715503plj.69.2017.01.10.15.48.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 10 Jan 2017 15:48:45 -0800 (PST) Date: Tue, 10 Jan 2017 15:48:44 -0800 From: Andrew Morton Subject: Re: [PATCH] mm: page_alloc: Skip over regions of invalid pfns where possible Message-Id: <20170110154844.e3fafdb927134b3737a6e1b0@linux-foundation.org> In-Reply-To: <0f03d5c6-182c-d30f-68ef-8d1a767bfcf8@imgtec.com> References: <20161125185518.29885-1-paul.burton@imgtec.com> <20170106144348.f7d207baa7b3190a95aaeb2e@linux-foundation.org> <0f03d5c6-182c-d30f-68ef-8d1a767bfcf8@imgtec.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: James Hartley Cc: Paul Burton , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Tue, 10 Jan 2017 23:37:53 +0000 James Hartley wrote: > > On 06/01/17 22:43, Andrew Morton wrote: > > On Fri, 25 Nov 2016 18:55:18 +0000 Paul Burton wrote: > > > >> When using a sparse memory model memmap_init_zone() when invoked with > >> the MEMMAP_EARLY context will skip over pages which aren't valid - ie. > >> which aren't in a populated region of the sparse memory map. However if > >> the memory map is extremely sparse then it can spend a long time > >> linearly checking each PFN in a large non-populated region of the memory > >> map & skipping it in turn. > >> > >> When CONFIG_HAVE_MEMBLOCK_NODE_MAP is enabled, we have sufficient > >> information to quickly discover the next valid PFN given an invalid one > >> by searching through the list of memory regions & skipping forwards to > >> the first PFN covered by the memory region to the right of the > >> non-populated region. Implement this in order to speed up > >> memmap_init_zone() for systems with extremely sparse memory maps. > > Could we have a changelog which includes some timing measurements? > > That permits others to understand the value of this patch. > > > I have tested this patch on a virtual model of a Samurai CPU with a > sparse memory map. The kernel boot time drops from 109 to 62 seconds. Thanks. Nice. I updated the changelog. -- 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