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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 676BCC38A2A for ; Fri, 8 May 2020 12:26:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F1C5207DD for ; Fri, 8 May 2020 12:26:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726864AbgEHM0i (ORCPT ); Fri, 8 May 2020 08:26:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726638AbgEHM0i (ORCPT ); Fri, 8 May 2020 08:26:38 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C03FFC05BD43 for ; Fri, 8 May 2020 05:26:37 -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 1jX25J-0004sf-3y; Fri, 08 May 2020 14:26:33 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 1FA61101175; Fri, 8 May 2020 14:26:32 +0200 (CEST) From: Thomas Gleixner To: Peter Zijlstra Cc: Josh Poimboeuf , x86@kernel.org, linux-kernel@vger.kernel.org, luto@kernel.org Subject: Re: [RFC][PATCH 3/3] x86/entry, ORC: Teach objtool/unwind_orc about stack irq swizzles In-Reply-To: <20200508101209.GY5298@hirez.programming.kicks-ass.net> References: <20200507161020.783541450@infradead.org> <20200507161828.801097834@infradead.org> <20200507173809.GK5298@hirez.programming.kicks-ass.net> <20200507183048.rlf2bgj4cf2g4jy6@treble> <878si3e8v2.fsf@nanos.tec.linutronix.de> <20200508101209.GY5298@hirez.programming.kicks-ass.net> Date: Fri, 08 May 2020 14:26:32 +0200 Message-ID: <87sggak3yf.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 Peter Zijlstra writes: > On Thu, May 07, 2020 at 11:24:49PM +0200, Thomas Gleixner wrote: >> But over our IRC conversation I came up with a 3rd variant: >> >> For most of the vectors the indirect call overhead is just noise, so >> we can run them through the ASM switcher, but for the resched IPI >> we can just use a separate direct call stub in ASM. > > Are we sure the rat-poison crap is noise for all the other system > vectors? I suppose it is for most since they'll do indirect calls > themselves anyway, right? We have different categories: 1) Uninteresting SPURIOUS_APIC_VECTOR, ERROR_APIC_VECTOR, THERMAL_APIC_VECTOR, THRESHOLD_APIC_VECTOR, REBOOT_VECTOR, DEFERRED_ERROR_VECTOR 2) Indirect call poisoned LOCAL_TIMER_VECTOR X86_PLATFORM_IPI_VECTOR IRQ_WORK_VECTOR HYPERV_STIMER0_VECTOR HYPERVISOR_CALLBACK_VECTOR POSTED_INTERRUPT_WAKEUP_VECTOR. CALL_FUNCTION_VECTOR CALL_FUNCTION_SINGLE_VECTOR 3) Quick RESCHEDULE_VECTOR POSTED_INTR_VECTOR POSTED_INTR_NESTED_VECTOR These two postit ones are weird because they are both empty and just increment different irq counts. HYPERV_REENLIGHTENMENT_VECTOR schedules delayed work, i,e. arms a timer which should be straight forward, but does it matter? 4) Others UV_BAU_MESSAGE - The TLB flushes are probably more expensive than ratpoutine Hmm? Thanks, tglx