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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E0BF6C0044D for ; Mon, 16 Mar 2020 15:37:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B189320663 for ; Mon, 16 Mar 2020 15:37:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731613AbgCPPhC (ORCPT ); Mon, 16 Mar 2020 11:37:02 -0400 Received: from foss.arm.com ([217.140.110.172]:50756 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731505AbgCPPhC (ORCPT ); Mon, 16 Mar 2020 11:37:02 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 400A51FB; Mon, 16 Mar 2020 08:37:01 -0700 (PDT) Received: from [10.37.9.38] (unknown [10.37.9.38]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 03C833F534; Mon, 16 Mar 2020 08:36:55 -0700 (PDT) Subject: Re: [PATCH v3 21/26] arm64: Introduce asm/vdso/arch_timer.h To: Catalin Marinas Cc: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, clang-built-linux@googlegroups.com, x86@kernel.org, Will Deacon , Arnd Bergmann , Russell King , Paul Burton , Thomas Gleixner , Andy Lutomirski , Ingo Molnar , Borislav Petkov , Stephen Boyd , Mark Salyzyn , Kees Cook , Peter Collingbourne , Dmitry Safonov <0x7f454c46@gmail.com>, Andrei Vagin , Nick Desaulniers , Marc Zyngier , Mark Rutland , Will Deacon References: <20200313154345.56760-1-vincenzo.frascino@arm.com> <20200313154345.56760-22-vincenzo.frascino@arm.com> <20200315183151.GE32205@mbp> From: Vincenzo Frascino Message-ID: <4914ad9c-3eaf-b328-f31b-5d3077ef272f@arm.com> Date: Mon, 16 Mar 2020 15:37:23 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200315183151.GE32205@mbp> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Catalin, On 3/15/20 6:32 PM, Catalin Marinas wrote: > On Fri, Mar 13, 2020 at 03:43:40PM +0000, Vincenzo Frascino wrote: >> The vDSO library should only include the necessary headers required for >> a userspace library (UAPI and a minimal set of kernel headers). To make >> this possible it is necessary to isolate from the kernel headers the >> common parts that are strictly necessary to build the library. >> >> Introduce asm/vdso/arch_timer.h to contain all the arm64 specific >> code. This allows to replace the second isb() in __arch_get_hw_counter() >> with a fake dependent stack read of the counter which improves the vdso >> library peformances of ~4.5%. Below the results of vdsotest [1] ran for >> 100 iterations. > > The subject seems to imply a non-functional change but as you read, it > gets a lot more complicated. Could you keep the functional change > separate from the header clean-up, maybe submit it as an independent > patch? And it shouldn't go in without Will's ack ;). > It is fine by me. I will repost the series with the required fixes and without this patch. This will give to me enough time to address Mark's comments as well and to Will to have a proper look. -- Regards, Vincenzo