Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751814Ab3JURbl (ORCPT ); Mon, 21 Oct 2013 13:31:41 -0400 Received: from mail-pd0-f178.google.com ([209.85.192.178]:33560 "EHLO mail-pd0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751449Ab3JURbk (ORCPT ); Mon, 21 Oct 2013 13:31:40 -0400 Message-ID: <1382376698.3284.68.camel@edumazet-glaptop.roam.corp.google.com> Subject: Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's From: Eric Dumazet To: Neil Horman Cc: Ingo Molnar , linux-kernel@vger.kernel.org, sebastien.dugue@bull.net, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org Date: Mon, 21 Oct 2013 10:31:38 -0700 In-Reply-To: <20131020212910.GA3387@neilslaptop.think-freely.org> References: <20131012172124.GA18241@gmail.com> <20131014202854.GH26880@hmsreliant.think-freely.org> <1381785560.2045.11.camel@edumazet-glaptop.roam.corp.google.com> <1381789127.2045.22.camel@edumazet-glaptop.roam.corp.google.com> <20131017003421.GA31470@hmsreliant.think-freely.org> <1381974128.2045.144.camel@edumazet-glaptop.roam.corp.google.com> <20131018165034.GC4019@hmsreliant.think-freely.org> <1382116835.3284.23.camel@edumazet-glaptop.roam.corp.google.com> <20131018201133.GD4019@hmsreliant.think-freely.org> <1382130952.3284.43.camel@edumazet-glaptop.roam.corp.google.com> <20131020212910.GA3387@neilslaptop.think-freely.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1284 Lines: 39 On Sun, 2013-10-20 at 17:29 -0400, Neil Horman wrote: > On Fri, Oct 18, 2013 at 02:15:52PM -0700, Eric Dumazet wrote: > > On Fri, 2013-10-18 at 16:11 -0400, Neil Horman wrote: > > > > > #define BUFSIZ_ORDER 4 > > > #define BUFSIZ ((2 << BUFSIZ_ORDER) * (1024*1024*2)) > > > static int __init csum_init_module(void) > > > { > > > int i; > > > __wsum sum = 0; > > > struct timespec start, end; > > > u64 time; > > > struct page *page; > > > u32 offset = 0; > > > > > > page = alloc_pages((GFP_TRANSHUGE & ~__GFP_MOVABLE), BUFSIZ_ORDER); > > > > Not sure what you are doing here, but its not correct. > > > Why not? You asked for a test with 32 hugepages, so I allocated 32 hugepages. Not really. We cannot allocate 64 Mbytes in a single alloc_pages() call on x86. (MAX_ORDER = 11) You noticed nothing because you did not write anything on the 64Mbytes area (and corrupt memory) or use CONFIG_DEBUG_PAGEALLOC=y. Your code read data out of bounds and was lucky, thats all... You in fact allocated a page of (4096<<4) bytes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/