From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vincenzo Frascino Subject: Re: [PATCH v3 21/26] arm64: Introduce asm/vdso/arch_timer.h Date: Thu, 9 Apr 2020 14:36:48 +0100 Message-ID: References: <20200313154345.56760-1-vincenzo.frascino@arm.com> <20200313154345.56760-22-vincenzo.frascino@arm.com> <20200315183151.GE32205@mbp> <4914ad9c-3eaf-b328-f31b-5d3077ef272f@arm.com> <20200409132633.GD13078@willie-the-truck> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from foss.arm.com ([217.140.110.172]:50244 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726597AbgDINgI (ORCPT ); Thu, 9 Apr 2020 09:36:08 -0400 In-Reply-To: <20200409132633.GD13078@willie-the-truck> Content-Language: en-US Sender: linux-arch-owner@vger.kernel.org List-ID: To: Will Deacon Cc: Catalin Marinas , 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 Hi Will, On 4/9/20 2:26 PM, Will Deacon wrote: > Hi Vincenzo, > > Sorry, I was on holiday when you posted this and it slipped through the > cracks. > No issue at all. Thank you for getting back to me. > On Mon, Mar 16, 2020 at 03:37:23PM +0000, Vincenzo Frascino 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. > > Please can you post whatever is left at -rc1? I'll have a look then, but > let's stick to just moving code around rather than randomly changing it > at the same time, ok? > Sure, I will try to re-post it by -rc1 and take on board your comments. > Thanks, > > Will > -- Regards, Vincenzo From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.110.172]:50244 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726597AbgDINgI (ORCPT ); Thu, 9 Apr 2020 09:36:08 -0400 Subject: Re: [PATCH v3 21/26] arm64: Introduce asm/vdso/arch_timer.h References: <20200313154345.56760-1-vincenzo.frascino@arm.com> <20200313154345.56760-22-vincenzo.frascino@arm.com> <20200315183151.GE32205@mbp> <4914ad9c-3eaf-b328-f31b-5d3077ef272f@arm.com> <20200409132633.GD13078@willie-the-truck> From: Vincenzo Frascino Message-ID: Date: Thu, 9 Apr 2020 14:36:48 +0100 MIME-Version: 1.0 In-Reply-To: <20200409132633.GD13078@willie-the-truck> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Will Deacon Cc: Catalin Marinas , 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 Message-ID: <20200409133648.D5yXPxhsghYMdB8YxybKIBWwFxQZOdIAezHMI2vxarw@z> Hi Will, On 4/9/20 2:26 PM, Will Deacon wrote: > Hi Vincenzo, > > Sorry, I was on holiday when you posted this and it slipped through the > cracks. > No issue at all. Thank you for getting back to me. > On Mon, Mar 16, 2020 at 03:37:23PM +0000, Vincenzo Frascino 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. > > Please can you post whatever is left at -rc1? I'll have a look then, but > let's stick to just moving code around rather than randomly changing it > at the same time, ok? > Sure, I will try to re-post it by -rc1 and take on board your comments. > Thanks, > > Will > -- Regards, Vincenzo