Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751262AbdCYV0f (ORCPT ); Sat, 25 Mar 2017 17:26:35 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:44064 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750915AbdCYV0d (ORCPT ); Sat, 25 Mar 2017 17:26:33 -0400 Date: Sat, 25 Mar 2017 14:25:58 -0700 From: Matthew Wilcox To: Pavel Tatashin Cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, heiko.carstens@de.ibm.com, davem@davemloft.net Subject: Re: [v2 0/5] parallelized "struct page" zeroing Message-ID: <20170325212558.GA1288@bombadil.infradead.org> References: <1490383192-981017-1-git-send-email-pasha.tatashin@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1490383192-981017-1-git-send-email-pasha.tatashin@oracle.com> User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1491 Lines: 34 On Fri, Mar 24, 2017 at 03:19:47PM -0400, Pavel Tatashin wrote: > Changelog: > v1 - v2 > - Per request, added s390 to deferred "struct page" zeroing > - Collected performance data on x86 which proofs the importance to > keep memset() as prefetch (see below). > > When deferred struct page initialization feature is enabled, we get a > performance gain of initializing vmemmap in parallel after other CPUs are > started. However, we still zero the memory for vmemmap using one boot CPU. > This patch-set fixes the memset-zeroing limitation by deferring it as well. > > Performance gain on SPARC with 32T: > base: https://hastebin.com/ozanelatat.go > fix: https://hastebin.com/utonawukof.go > > As you can see without the fix it takes: 97.89s to boot > With the fix it takes: 46.91 to boot. > > Performance gain on x86 with 1T: > base: https://hastebin.com/uvifasohon.pas > fix: https://hastebin.com/anodiqaguj.pas > > On Intel we save 10.66s/T while on SPARC we save 1.59s/T. Intel has > twice as many pages, and also fewer nodes than SPARC (sparc 32 nodes, vs. > intel 8 nodes). > > It takes one thread 11.25s to zero vmemmap on Intel for 1T, so it should > take additional 11.25 / 8 = 1.4s (this machine has 8 nodes) per node to > initialize the memory, but it takes only additional 0.456s per node, which > means on Intel we also benefit from having memset() and initializing all > other fields in one place. My question was how long it takes if you memset in neither place.