From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-1.mimecast.com ([207.211.31.81]:44989 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726505AbfKORq7 (ORCPT ); Fri, 15 Nov 2019 12:46:59 -0500 Date: Fri, 15 Nov 2019 11:46:49 -0600 From: Josh Poimboeuf Subject: Re: [RFC PATCH v3 7/7] x86/unwind/orc: remove run-time ORC unwind tables sort Message-ID: <20191115174649.ldif5o7xqo5ntxeo@treble> References: <20191115064750.47888-1-shile.zhang@linux.alibaba.com> <20191115064750.47888-8-shile.zhang@linux.alibaba.com> <893d3caf85cd4ed0921fab84cfe28cad@AcuMS.aculab.com> MIME-Version: 1.0 In-Reply-To: <893d3caf85cd4ed0921fab84cfe28cad@AcuMS.aculab.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: David Laight Cc: 'Shile Zhang' , Peter Zijlstra , Masahiro Yamada , Michal Marek , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "x86@kernel.org" , "H . Peter Anvin" , "linux-kernel@vger.kernel.org" , "linux-kbuild@vger.kernel.org" On Fri, Nov 15, 2019 at 04:51:24PM +0000, David Laight wrote: > From: Shile Zhang > > Sent: 15 November 2019 06:48 > ... > > arch/x86/kernel/unwind_orc.c | 8 +++++--- > > 1 file changed, 5 insertions(+), 3 deletions(-) > >=20 > > 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) > > =09=09return; > > =09} > >=20 > > -=09/* Sort the .orc_unwind and .orc_unwind_ip tables: */ > > -=09sort(__start_orc_unwind_ip, num_entries, sizeof(int), orc_sort_cmp, > > -=09 orc_sort_swap); > > +=09/* > > +=09 * Note, orc_unwind and orc_unwind_ip tables has been sorted in > > +=09 * vmlinux link phase by sorttable tool at build time. > > +=09 * Its ready for binary search now. > > +=09 */ >=20 > How fast is sort() if the table is sorted? > Relying on the kernel sources and build scripts always being in sync seem= s dangerous. > Probably better to leave the sort in for a release of two. This patch comes after the build script changes, so they'd be in sync. What would the concern be? --=20 Josh