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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,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 DA744C43141 for ; Fri, 15 Nov 2019 16:51:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE09820730 for ; Fri, 15 Nov 2019 16:51:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727744AbfKOQva convert rfc822-to-8bit (ORCPT ); Fri, 15 Nov 2019 11:51:30 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:35163 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727555AbfKOQva (ORCPT ); Fri, 15 Nov 2019 11:51:30 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-28-JYU6DzG4PJauNrdBTvHnwQ-1; Fri, 15 Nov 2019 16:51:25 +0000 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; Fri, 15 Nov 2019 16:51:24 +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; Fri, 15 Nov 2019 16:51:24 +0000 From: David Laight To: 'Shile Zhang' , Peter Zijlstra , Josh Poimboeuf , Masahiro Yamada , Michal Marek , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "x86@kernel.org" CC: "H . Peter Anvin" , "linux-kernel@vger.kernel.org" , "linux-kbuild@vger.kernel.org" Subject: RE: [RFC PATCH v3 7/7] x86/unwind/orc: remove run-time ORC unwind tables sort Thread-Topic: [RFC PATCH v3 7/7] x86/unwind/orc: remove run-time ORC unwind tables sort Thread-Index: AQHVm4CqL2sS2uy4n0+BG1AUQK0Os6eMck/g Date: Fri, 15 Nov 2019 16:51:24 +0000 Message-ID: <893d3caf85cd4ed0921fab84cfe28cad@AcuMS.aculab.com> References: <20191115064750.47888-1-shile.zhang@linux.alibaba.com> <20191115064750.47888-8-shile.zhang@linux.alibaba.com> In-Reply-To: <20191115064750.47888-8-shile.zhang@linux.alibaba.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-MC-Unique: JYU6DzG4PJauNrdBTvHnwQ-1 X-Mimecast-Spam-Score: 0 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: Shile Zhang > Sent: 15 November 2019 06:48 ... > arch/x86/kernel/unwind_orc.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c > index 332ae6530fa8..280da6fa9922 100644 > --- a/arch/x86/kernel/unwind_orc.c > +++ b/arch/x86/kernel/unwind_orc.c > @@ -273,9 +273,11 @@ void __init unwind_init(void) > return; > } > > - /* Sort the .orc_unwind and .orc_unwind_ip tables: */ > - sort(__start_orc_unwind_ip, num_entries, sizeof(int), orc_sort_cmp, > - orc_sort_swap); > + /* > + * Note, orc_unwind and orc_unwind_ip tables has been sorted in > + * vmlinux link phase by sorttable tool at build time. > + * Its ready for binary search now. > + */ How fast is sort() if the table is sorted? Relying on the kernel sources and build scripts always being in sync seems dangerous. Probably better to leave the sort in for a release of two. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)