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=-3.8 required=3.0 tests=BAYES_00, 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 354DCC433DF for ; Thu, 27 Aug 2020 14:56:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18F9622B4B for ; Thu, 27 Aug 2020 14:56:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728098AbgH0O40 convert rfc822-to-8bit (ORCPT ); Thu, 27 Aug 2020 10:56:26 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]:38606 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726084AbgH0NHp (ORCPT ); Thu, 27 Aug 2020 09:07:45 -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-193-ebJTYPNPMbe2YTXzj0WrTA-1; Thu, 27 Aug 2020 14:07:34 +0100 X-MC-Unique: ebJTYPNPMbe2YTXzj0WrTA-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; Thu, 27 Aug 2020 14:07:33 +0100 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; Thu, 27 Aug 2020 14:07:33 +0100 From: David Laight To: 'Matthew Wilcox' , Shaokun Zhang CC: "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Yuqi Jin , Will Deacon , Mark Rutland Subject: RE: [PATCH] fs: Optimized fget to improve performance Thread-Topic: [PATCH] fs: Optimized fget to improve performance Thread-Index: AQHWfHA0Q0HraGCxZUqID6ug/Nw0ZqlL69xQ Date: Thu, 27 Aug 2020 13:07:33 +0000 Message-ID: <6feef2f0b6ed4df99e66c8325c8e66ae@AcuMS.aculab.com> References: <1598523584-25601-1-git-send-email-zhangshaokun@hisilicon.com> <20200827123040.GE14765@casper.infradead.org> In-Reply-To: <20200827123040.GE14765@casper.infradead.org> 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 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0.001 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: Matthew Wilcox > Sent: 27 August 2020 13:31 > On Thu, Aug 27, 2020 at 06:19:44PM +0800, Shaokun Zhang wrote: > > From: Yuqi Jin > > > > It is well known that the performance of atomic_add is better than that of > > atomic_cmpxchg. > > I don't think that's well-known at all. Especially since on (probably) every architecture except x86 atomic_add() is implemented using atomic_cmpxchg(). David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)