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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D67DEC54E76 for ; Tue, 17 Jan 2023 19:10:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232287AbjAQTKU (ORCPT ); Tue, 17 Jan 2023 14:10:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42922 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232774AbjAQTHX (ORCPT ); Tue, 17 Jan 2023 14:07:23 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64F695A371 for ; Tue, 17 Jan 2023 10:21:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=unmKUMBNwOXHvAndehV7v/2JxDCOLUZsRo+qdzYFj6A=; b=n0jfxOM3FQiFZJqzalSvUFm+hO ZhdQcBgFrC4WuybQ7vqhCBQ5vnriNnOBC/Wf/3VU4G/PLdgtCKjQ8p8fJlwFrxjFnucdKs2jBoOh6 +8khK/X161uXMNtiyqPYR7y12+s5aXi2Cuo4kyY+2/meTLEenKUBekl05VIcOKI4jwPy4cVLAgBo+ sdt5uFvqPtGv/w9QX6Pn0BUf09bGuLbg4lQK8E7xz8jjhimia8STgLuXB5yqUj3Avpzqc0b2W5ILV nj1xiC7F/2/+yi9kHLyVI88rH2A6PRWQFt+apqQLA81gb9d03HuPEEQYwEe4x/OfxXtjUrghi9gR4 nabVIXkw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1pHqaT-009u5G-JV; Tue, 17 Jan 2023 18:21:33 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id B0A9E30030F; Tue, 17 Jan 2023 19:21:18 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 98FCC210FFF6D; Tue, 17 Jan 2023 19:21:18 +0100 (CET) Date: Tue, 17 Jan 2023 19:21:18 +0100 From: Peter Zijlstra To: Linus Torvalds Cc: "Kirill A. Shutemov" , Dave Hansen , Andy Lutomirski , x86@kernel.org, Kostya Serebryany , Andrey Ryabinin , Andrey Konovalov , Alexander Potapenko , Taras Madan , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , Bharata B Rao , Jacob Pan , Ashok Raj , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sami Tolvanen , ndesaulniers@google.com, joao@overdrivepizza.com Subject: Re: [PATCHv14 08/17] x86/mm: Reduce untagged_addr() overhead until the first LAM user Message-ID: References: <20230111123736.20025-1-kirill.shutemov@linux.intel.com> <20230111123736.20025-9-kirill.shutemov@linux.intel.com> <20230117135703.voaumisreld7crfb@box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 17, 2023 at 09:18:01AM -0800, Linus Torvalds wrote: > But maybe even those aren't worth worrying about. At least they do the > unmasking outside the loop - although then in the case of execve(), > the string copies themselves are obviously done in a loop anyway. > > Kirill, do you have clear numbers for that static key being a noticeable win? Numbers would be good; I think this all started as a precaution, but clearly that's not really working out so well :/