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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham 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 41762C4360F for ; Tue, 2 Apr 2019 15:51:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F88320645 for ; Tue, 2 Apr 2019 15:51:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729958AbfDBPvw (ORCPT ); Tue, 2 Apr 2019 11:51:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:24601 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726716AbfDBPvw (ORCPT ); Tue, 2 Apr 2019 11:51:52 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 38F2E3082B71; Tue, 2 Apr 2019 15:51:52 +0000 (UTC) Received: from treble (ovpn-122-147.rdu2.redhat.com [10.10.122.147]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9B8CD8491D; Tue, 2 Apr 2019 15:51:51 +0000 (UTC) Date: Tue, 2 Apr 2019 10:51:49 -0500 From: Josh Poimboeuf To: Thomas Gleixner Cc: LKML , x86@kernel.org, Andy Lutomirski Subject: Re: [patch 15/14] x86/dumpstack/64: Speedup in_exception_stack() Message-ID: <20190402155149.c23ivzzc5hyykokl@treble> References: <20190331214020.836098943@linutronix.de> <20190331215136.039902969@linutronix.de> <20190402154329.scp7i7uqevubgwrz@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Tue, 02 Apr 2019 15:51:52 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 02, 2019 at 05:48:56PM +0200, Thomas Gleixner wrote: > > With the above "(stk <= begin || stk >= end)" check, removing the loop > > becomes not all that important since exception stack dumps are quite > > rare and not performance sensitive. With all the macros this code > > becomes a little more obtuse, so I'm not sure whether removal of the > > loop is a net positive. > > What about perf? It's NMI context and probably starts from there. Peter? I believe perf unwinds starting from the regs from the context which was interrupted by the NMI. -- Josh