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, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 EAA97C433DF for ; Fri, 15 May 2020 09:35:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B727320643 for ; Fri, 15 May 2020 09:35:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728113AbgEOJf2 (ORCPT ); Fri, 15 May 2020 05:35:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44876 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1727803AbgEOJf1 (ORCPT ); Fri, 15 May 2020 05:35:27 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 75C0AC061A0C for ; Fri, 15 May 2020 02:35:27 -0700 (PDT) Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jZWjz-00049l-9B; Fri, 15 May 2020 11:34:51 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id B1E28100606; Fri, 15 May 2020 11:34:50 +0200 (CEST) From: Thomas Gleixner To: Mathieu Desnoyers Cc: linux-kernel , x86 , paulmck , Andy Lutomirski , Alexandre Chartre , Frederic Weisbecker , Paolo Bonzini , Sean Christopherson , Masami Hiramatsu , Petr Mladek , rostedt , "Joel Fernandes\, Google" , Boris Ostrovsky , Juergen Gross , Brian Gerst , Josh Poimboeuf , Will Deacon Subject: Re: [patch V4 part 1 14/36] x86/entry: Get rid of ist_begin/end_non_atomic() In-Reply-To: <1777514130.20137.1589410645669.JavaMail.zimbra@efficios.com> References: <20200505131602.633487962@linutronix.de> <20200505134059.462640294@linutronix.de> <1777514130.20137.1589410645669.JavaMail.zimbra@efficios.com> Date: Fri, 15 May 2020 11:34:50 +0200 Message-ID: <877dxdy211.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mathieu Desnoyers writes: > ----- On May 5, 2020, at 9:16 AM, Thomas Gleixner tglx@linutronix.de wrote: > >> This is completely overengineered and definitely not an interface which >> should be made available to anything else than this particular MCE case. > > This patch introduces a significant change under the radar (not explained > in the changelog): it turns preempt_enable_no_resched() into preempt_enable(). > > Why, and why was it a no_resched() in the first place ? Was it for performance > or correctness reasons ? _no_resched() is an optimization when in code which cannot schedule anyway. But #MC is definitely not a performance critical hotpath. So yes, it's a change but really not significant. >> Signed-off-by: Thomas Gleixner >> --- < Remove useless gunk > Can you please trim your replies? Thanks, tglx