From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752562AbdJTNjz (ORCPT ); Fri, 20 Oct 2017 09:39:55 -0400 Received: from mx2.suse.de ([195.135.220.15]:46383 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751642AbdJTNjy (ORCPT ); Fri, 20 Oct 2017 09:39:54 -0400 Date: Fri, 20 Oct 2017 15:39:49 +0200 (CEST) From: Miroslav Benes To: Josh Poimboeuf cc: Torsten Duwe , Joao Moreira , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, mmarek@suse.cz, pmladek@suse.com, jikos@suse.cz, nstange@suse.de, jroedel@suse.de, matz@suse.de, khlebnikov@yandex-team.ru, jeyu@kernel.org Subject: Re: [PATCH 0/8] livepatch: klp-convert tool In-Reply-To: <20171020132432.majphjzzfrbcrdos@treble> Message-ID: References: <20171011024615.y55lwbgpgo6b5dll@treble> <14124e34-04f7-950e-72fb-64f13e62f57e@suse.de> <20171019130146.uxjuhgn2t3yavgz2@treble> <20171019140338.pngwewyzllaw2wu5@treble> <20171019151522.5ih3egvzr3wm3h7r@treble> <20171020124432.GB20306@lst.de> <20171020132432.majphjzzfrbcrdos@treble> User-Agent: Alpine 2.21 (LSU 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > For -fpatchable-function-entries I switched > > off IPA-RA, as especially on RISC there's _nothing_ you can do between > > functions without at least one scratch reg. But for live patching, I'd like > > the kernel to be compiled in the first place with 100% ABI adherence, IOW > > all IPA optimisations turned off. Does anyone have numbers on the performance > > impact? > > I agree that would be the best option. > > I don't think anyone has measured it because we don't know how to get > the compiler to do that :-) My guess is that it will be something close > to negligible. I asked Nicolai to do some performance testing with all the options that could be disabled disabled. Miroslav