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 BB2C9C3DA78 for ; Tue, 17 Jan 2023 13:05:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236632AbjAQNFy (ORCPT ); Tue, 17 Jan 2023 08:05:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48020 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236788AbjAQNFu (ORCPT ); Tue, 17 Jan 2023 08:05:50 -0500 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85F1930EA3 for ; Tue, 17 Jan 2023 05:05:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=Jme9zz2lpphQFdQzWSwDey8PeXCFcOvKT0bkE6Mbk38=; b=Ba3guL0BWUgd+jP/llCnOAhXLF Hnv6WeFYTdqcpMKQlUG9YGrc0FO1Bv3t7ux7SiCcujeC1p1NOV6VZ0bNJpfJ7wT/j62DCMuGfUNFD RvkZjmcqXsXp5GGw/QCeOt+zQia8tysEgFE7TZQxtwXbqJp0F5I2HmEVxEuQdtdyX4DNpzrRHXCl7 /CV2MTTSradvHELrV5oyiE2gadTyfn5NJiN3qbNHX0RzEqMh3z9BJFkQj3uqk/MFkolkUQ9TysK3+ E64xzeM9j+54aHPwWsl41/OSc3ueHtPADUWus2j2m5f4zJe06yEMjdZfZs2t3IQqHReZRwPLFdNSx sJqMYJIA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1pHleN-005wDX-0T; Tue, 17 Jan 2023 13:05:15 +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) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id A6581300094; Tue, 17 Jan 2023 14:05:22 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7A24B264FC770; Tue, 17 Jan 2023 14:05:22 +0100 (CET) Date: Tue, 17 Jan 2023 14:05:22 +0100 From: Peter Zijlstra To: "Kirill A. Shutemov" Cc: 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 , Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230111123736.20025-9-kirill.shutemov@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 11, 2023 at 03:37:27PM +0300, Kirill A. Shutemov wrote: > #define __untagged_addr(untag_mask, addr) ({ \ > u64 __addr = (__force u64)(addr); \ > - s64 sign = (s64)__addr >> 63; \ > - __addr &= untag_mask | sign; \ > + if (static_branch_likely(&tagged_addr_key)) { \ > + s64 sign = (s64)__addr >> 63; \ > + __addr &= untag_mask | sign; \ > + } \ > (__force __typeof__(addr))__addr; \ > }) > > #define untagged_addr(addr) __untagged_addr(current_untag_mask(), addr) Is the compiler clever enough to put the memop inside the branch?