From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 8 Aug 2018 13:10:13 +0200 From: Vasily Gorbik Subject: Re: [PATCH 4/4] s390/ftrace: add -mfentry and -mnop-mcount support References: <20180807053017.GA6613@osiris> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180807053017.GA6613@osiris> Message-Id: Sender: linux-kbuild-owner@vger.kernel.org List-Archive: List-Post: To: Heiko Carstens Cc: Masahiro Yamada , Michal Marek , Martin Schwidefsky , Steven Rostedt , Ingo Molnar , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Andi Kleen List-ID: On Tue, Aug 07, 2018 at 07:30:17AM +0200, Heiko Carstens wrote: > On Mon, Aug 06, 2018 at 03:17:47PM +0200, Vasily Gorbik wrote: > > Utilize -mfentry and -mnop-mcount gcc options together with > > -mrecord-mcount to get compiler generated calls to the profiling functions > > as nops which are compatible with current -mhotpatch=0,3 approach. At the > > same time -mrecord-mcount enables __mcount_loc section generation by > > the compiler which allows to avoid using scripts/recordmcount.pl script. > > > > Signed-off-by: Vasily Gorbik > > --- > > arch/s390/Kconfig | 2 ++ > > arch/s390/Makefile | 16 +++++++++------- > > arch/s390/include/asm/ftrace.h | 6 +++--- > > arch/s390/kernel/ftrace.c | 2 +- > > arch/s390/kernel/mcount.S | 2 +- > > 5 files changed, 16 insertions(+), 12 deletions(-) > > Do you have numbers which tell how much this reduces the compile time of > the kernel on s390? I assume this change makes quite some difference. > Very roughly, best time across several runs. With -j24 on 24 core lpar with -mfentry -mrecord-mcount etc real 0m54.748s user 12m32.041s sys 1m17.778s vs -mhotpatch=0,3 + scripts/recordmcount.pl: real 0m56.752s user 12m52.386s sys 1m35.873s