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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED autolearn=ham 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 E7E16C282D7 for ; Sat, 2 Feb 2019 22:49:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B1EB120855 for ; Sat, 2 Feb 2019 22:49:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="Qv9MJb3h" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726770AbfBBWty (ORCPT ); Sat, 2 Feb 2019 17:49:54 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:42672 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726721AbfBBWty (ORCPT ); Sat, 2 Feb 2019 17:49:54 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x12MnEoN064432; Sat, 2 Feb 2019 22:49:39 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=content-type : mime-version : subject : from : in-reply-to : date : cc : content-transfer-encoding : message-id : references : to; s=corp-2018-07-02; bh=l75nnAArW2QDtkZzFdC5cFtjMMSgSahJrxPNCHfdRu8=; b=Qv9MJb3hGSUmHLUK5kYIo9P6qKAF4MGl1MBgZxacmgG3b+P/kDZtsAICOC5N3Bq/PNmg HT9a+HJ8LJ48DZc/DNzYItT2IvnN75/O3zYW2nsFlXZ3RUm2KP2B6wtkc/2GnXd6tRww atL3hzzGX6dsIIqL9VqFx1Gd3NJhTA/N9AJ8VG0PiJXzSIvXEH3aP38zrmGYNSr2N1kC GCh27kIjSiVXcZ1y1voW3dS+zkpdt2pil4/3Rabq1SlhwuyuECh36TLFZp5/6MrgPXX6 bgy7j2eCdbOulPBIfre1/9QuiSQtFtjDDpwT8aI3OwKfqV7zY6nwme28g8FRea69PbB5 sw== Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by userp2120.oracle.com with ESMTP id 2qd98mrt1y-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 02 Feb 2019 22:49:38 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id x12MncdF002851 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 2 Feb 2019 22:49:38 GMT Received: from abhmp0010.oracle.com (abhmp0010.oracle.com [141.146.116.16]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x12MnbcF024303; Sat, 2 Feb 2019 22:49:37 GMT Received: from anon-dhcp-171.1015granger.net (/68.61.232.219) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sat, 02 Feb 2019 22:49:37 +0000 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 12.2 \(3445.102.3\)) Subject: Re: [PATCH RFC 04/10] SUNRPC: Add common byte-swapped RPC header constants From: Chuck Lever In-Reply-To: <20190202170258.GA14074@infradead.org> Date: Sat, 2 Feb 2019 17:49:35 -0500 Cc: Linux NFS Mailing List , simo@redhat.com Content-Transfer-Encoding: 7bit Message-Id: <52468C38-9E9C-49A7-B44B-2BE302A33145@oracle.com> References: <20190201195538.11389.96106.stgit@manet.1015granger.net> <20190201195747.11389.75164.stgit@manet.1015granger.net> <20190202170258.GA14074@infradead.org> To: Christoph Hellwig X-Mailer: Apple Mail (2.3445.102.3) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9155 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=919 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902020190 Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org > On Feb 2, 2019, at 12:02 PM, Christoph Hellwig wrote: > > On Fri, Feb 01, 2019 at 02:57:47PM -0500, Chuck Lever wrote: >> Byte-swapping causes a CPU pipeline bubble on some processors. When >> a decoder is comparing an on-the-wire value for equality, byte- >> swapping can be avoided by comparing it directly to a pre-byte- >> swapped constant value. > > Which ones? I assume you mean on which processors have I observed CPU cycle spikes around bswap instructions. I've seen this behavior only on Intel processors of various families. Would you prefer a different justification for this clean-up? -- Chuck Lever