From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B87AC10F27 for ; Wed, 11 Mar 2020 15:07:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 64762206C0 for ; Wed, 11 Mar 2020 15:07:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729971AbgCKPHM convert rfc822-to-8bit (ORCPT ); Wed, 11 Mar 2020 11:07:12 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([146.101.78.151]:45810 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729954AbgCKPHL (ORCPT ); Wed, 11 Mar 2020 11:07:11 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-239-v-FOvOPCOYOtCUtaloZQVw-1; Wed, 11 Mar 2020 15:07:08 +0000 X-MC-Unique: v-FOvOPCOYOtCUtaloZQVw-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Wed, 11 Mar 2020 15:07:07 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Wed, 11 Mar 2020 15:07:07 +0000 From: David Laight To: 'Andi Kleen' , Michal Hocko CC: "Kirill A. Shutemov" , Cannon Matthews , Mike Kravetz , "Andrew Morton" , Matthew Wilcox , David Rientjes , Greg Thelen , Salman Qazi , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "x86@kernel.org" Subject: RE: [PATCH] mm: clear 1G pages with streaming stores on x86 Thread-Topic: [PATCH] mm: clear 1G pages with streaming stores on x86 Thread-Index: AQHV9ijM3XjXd8DH7k20GvQVG1posahDf+RQ Date: Wed, 11 Mar 2020 15:07:07 +0000 Message-ID: References: <20200307010353.172991-1-cannonmatthews@google.com> <20200309000820.f37opzmppm67g6et@box> <20200309090630.GC8447@dhcp22.suse.cz> <20200309153831.GK1454533@tassilo.jf.intel.com> In-Reply-To: <20200309153831.GK1454533@tassilo.jf.intel.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andi Kleen > Sent: 09 March 2020 15:39 ... > There's a cautious tale of the old crappy RAID5 XOR assembler functions which > were optimized a long time ago for the Pentium1, and stayed around, > even though the compiler could actually do a better job. Or the amd64 asm loop for doing the IP checksum. I doubt it was even the fastest version when it was written. A whole set of Intel cpus can run twice as fast as that version with less loop unrolling (and associated code for 'odd' lengths). David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)