From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 2C48BA034F; Tue, 23 Feb 2021 10:43:08 +0100 (CET) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id E0EA94067A; Tue, 23 Feb 2021 10:43:07 +0100 (CET) Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by mails.dpdk.org (Postfix) with ESMTP id 5A09640041 for ; Tue, 23 Feb 2021 10:43:06 +0100 (CET) IronPort-SDR: M46dYamQR6eDmeW26/jWT5gh2fTR5d9kqu5Od9Iog+dtO/9tTPm1xaLfzLaGidIiNWkksszL+L PrGit8tVdAJQ== X-IronPort-AV: E=McAfee;i="6000,8403,9903"; a="246167684" X-IronPort-AV: E=Sophos;i="5.81,199,1610438400"; d="scan'208";a="246167684" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Feb 2021 01:43:05 -0800 IronPort-SDR: aWxvRD3uRUfVn9DQHCvq0oJJgtk6stYGHCIaIfN5OJfXlgXOIQ4YIHWFiFRNLtsG+YASDxJcjC ZE3to4p2Pwag== X-IronPort-AV: E=Sophos;i="5.81,199,1610438400"; d="scan'208";a="403087513" Received: from bricha3-mobl.ger.corp.intel.com ([10.252.16.220]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-SHA; 23 Feb 2021 01:43:03 -0800 Date: Tue, 23 Feb 2021 09:43:00 +0000 From: Bruce Richardson To: Juraj =?utf-8?Q?Linke=C5=A1?= Cc: David Christensen , "thomas@monjalon.net" , "Honnappa.Nagarahalli@arm.com" , "dev@dpdk.org" Message-ID: <20210223094300.GA79@bricha3-MOBL.ger.corp.intel.com> References: <1606405649-4308-1-git-send-email-juraj.linkes@pantheon.tech> <1609761130-4627-1-git-send-email-juraj.linkes@pantheon.tech> <2c52c961e32643f385c9ce76d9d78236@pantheon.tech> <1be8e489-db41-c0d6-8518-d2844c8145c4@linux.vnet.ibm.com> <20210106144249.GB1969@bricha3-MOBL.ger.corp.intel.com> <1ab99ff8a97e4341830f17cce45d47db@pantheon.tech> <4b487ebe-0069-1c1e-087e-c23b865e779a@linux.vnet.ibm.com> <437e07673881422296387a9822298b4f@pantheon.tech> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <437e07673881422296387a9822298b4f@pantheon.tech> Subject: Re: [dpdk-dev] [RFC PATCH v2] build: add platform meson option X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Tue, Feb 23, 2021 at 08:45:09AM +0000, Juraj Linkeš wrote: > > > > -----Original Message----- > > From: David Christensen > > Sent: Monday, February 22, 2021 10:25 PM > > To: Juraj Linkeš ; Bruce Richardson > > > > Cc: thomas@monjalon.net; Honnappa.Nagarahalli@arm.com; dev@dpdk.org > > Subject: Re: [RFC PATCH v2] build: add platform meson option > > > > > > > > On 2/19/21 1:11 AM, Juraj Linkeš wrote: > > > > > > > > >> -----Original Message----- > > >> From: Bruce Richardson > > >> Sent: Wednesday, January 6, 2021 3:43 PM > > >> To: David Christensen > > >> Cc: Juraj Linkeš ; thomas@monjalon.net; > > >> Honnappa.Nagarahalli@arm.com; dev@dpdk.org > > >> Subject: Re: [RFC PATCH v2] build: add platform meson option > > >> > > >> On Tue, Jan 05, 2021 at 02:17:44PM -0800, David Christensen wrote: > > >>>>> The current meson option 'machine' should only specify the ISA, > > >>>>> which is not sufficient for Arm, where setting ISA implies other > > >>>>> setting as > > >> well. > > >>>>> Add a new meson option, 'platform', which differentiates the type > > >>>>> of the build > > >>>>> (native/generic) and sets machine accordingly, unless the user > > >>>>> chooses to override it. > > >>>>> The 'machine' option also doesn't describe very well what it sets, > > >>>>> so introduce a new option 'cpu_instruction_set', but keep > > >>>>> 'machine' for backward compatibility. > > >>>>> These two new variables, taken together, achieve what 'machine' > > >>>>> was setting per architecture - setting the ISA in x86 build and > > >>>>> setting native/default 'build type' in aarch64 build - is now > > >>>>> properly being set for all architectures in a uniform manner. > > >>>>> > > >>>>> Signed-off-by: Juraj Linkeš > > >>>>> --- > > >>>>> config/arm/meson.build | 4 +-- > > >>>>> config/meson.build | 47 +++++++++++++++++++++++++---------- > > >>>>> devtools/test-meson-builds.sh | 9 ++++--- > > >>>>> meson_options.txt | 8 ++++-- > > >>>>> 4 files changed, 47 insertions(+), 21 deletions(-) > > >>>>> > > >>>>> diff --git a/config/arm/meson.build b/config/arm/meson.build index > > >>>>> 42b4e43c7..6b09a74a7 100644 > > >>>>> --- a/config/arm/meson.build > > >>>>> +++ b/config/arm/meson.build > > >>>>> @@ -3,10 +3,10 @@ > > >>>>> # Copyright(c) 2017 Cavium, Inc > > >>>>> > > >>>>> # for checking defines we need to use the correct compiler > > >>>>> flags -march_opt = '- > > >>>>> march=@0@'.format(machine) > > >>>>> +march_opt = '-march=@0@'.format(cpu_instruction_set) > > >>>>> > > >>>>> arm_force_native_march = false > > >>>>> -arm_force_default_march = (machine == 'default') > > >>>>> +arm_force_default_march = (platform == 'generic') > > >>>>> > > >>>>> flags_common_default = [ > > >>>>> # Accelarate rte_memcpy. Be sure to run unit test > > >>>>> (memcpy_perf_autotest) diff --git a/config/meson.build > > >>>>> b/config/meson.build index a3154e29c..647116513 100644 > > >>>>> --- a/config/meson.build > > >>>>> +++ b/config/meson.build > > >>>>> @@ -63,42 +63,63 @@ if not is_windows > > >>>>> pmd_subdir_opt) > > >>>>> endif > > >>>>> > > >>>>> -# set the machine type and cflags for it > > >>>>> +platform = get_option('platform') > > >>>>> + > > >>>>> +# set the cpu_instruction_set type and cflags for it > > >>>>> if meson.is_cross_build() > > >>>>> - machine = host_machine.cpu() > > >>>>> + cpu_instruction_set = host_machine.cpu() > > >>>>> else > > >>>>> - machine = get_option('machine') > > >>>>> + cpu_instruction_set = get_option('cpu_instruction_set') > > >>>>> + if get_option('machine') != 'auto' > > >>>>> + warning('The "machine" option is deprecated. ' + > > >>>>> + 'Please use "cpu_instruction_set" instead.') > > >>>>> + if cpu_instruction_set != 'auto' > > >>>>> + error('Setting both "machine" and ' + > > >>>>> + '"cpu_instruction_set" is unsupported.') > > >>>>> + endif > > >>>>> + cpu_instruction_set = get_option('machine') > > >>>>> + endif > > >>>>> +endif > > >>>>> + > > >>>>> +if platform == 'native' > > >>>>> + if cpu_instruction_set == 'auto' > > >>>>> + cpu_instruction_set = 'native' > > >>>>> + endif > > >>>>> +elif platform == 'generic' > > >>>>> + if cpu_instruction_set == 'auto' > > >>>>> + cpu_instruction_set = 'default' > > >>>>> + endif > > >>>>> endif > > >>>>> > > >>>>> -# machine type 'default' is special, it defaults to the per arch > > >>>>> agreed common > > >>>>> +if cpu_instruction_set == 'default' > > >>>>> +# cpu_instruction_set type 'default' is special, it defaults to > > >>>>> +the per arch agreed common > > >>>>> # minimal baseline needed for DPDK. > > >>>>> # That might not be the most optimized, but the most portable > > >>>>> version while # still being able to support the CPU features > > >>>>> required for > > >> DPDK. > > >>>>> # This can be bumped up by the DPDK project, but it can never > > >>>>> be an # invariant like 'native' > > >>>>> -if machine == 'default' > > >>>>> if host_machine.cpu_family().startswith('x86') > > >>>>> # matches the old pre-meson build systems default > > >>>>> - machine = 'corei7' > > >>>>> + cpu_instruction_set = 'corei7' > > >>>>> elif host_machine.cpu_family().startswith('arm') > > >>>>> - machine = 'armv7-a' > > >>>>> + cpu_instruction_set = 'armv7-a' > > >>>>> elif host_machine.cpu_family().startswith('aarch') > > >>>>> # arm64 manages defaults in config/arm/meson.build > > >>>>> - machine = 'default' > > >>>>> + cpu_instruction_set = 'default' > > >>>>> elif host_machine.cpu_family().startswith('ppc') > > >>>>> - machine = 'power8' > > >>>>> + cpu_instruction_set = 'power8' > > >>>>> endif > > >>>>> endif > > >>> > > >>> This change forces the build on a P9 system to use the P8 instruction set. > > >>> Prior to this change the "native" machine type was used which > > >>> resulted in P9 instructions when built on a P9 system. How do I > > >>> force the build to use the > > >>> power9 instruction set in this case? > > >>> > > >>> Dave > > >> > > >> From looking at the patch, setting the "platform" to "native", or > > >> the instruction_set to "native" should do this. > > >> While I consider generic builds a good thing, I wonder if there is an > > >> expectation that "native" is always the default build type for DPDK builds? > > >> > > >> /Bruce > > > > > > I left this patch alone so that people could chime in, but noone did, so let's try > > to find some agreeable solution. > > > > > > My current thoughts are as such: > > > The platform parameter specifies a set of DPDK options that will be used. This > > is what arm uses for its builds, x86 and ppc don't use this. > > > The cpu_instruction_set sets just one configuration among the "platform" > > configuration set. > > > We want the build to work on most machines of the machine architecture. > > That implies platform=generic (as in use config options that will work on > > everything of that architecture) and cpu_instruction_set=generic (as in use ISA > > that will work on all cpus of the build machine architecture). > > > Setting cpu_instruction_set=generic changes the build without cmdline options > > for ppc. Thus, the expectation may be that cpu_instruction_set should be native > > by default. > > > > > > For arm, cpu_instruction_set is ignored (and thus the value doen't matter), > > since we can't use that without other config options (e.g. DPDK config for an > > SoC (such as RTE_ARM_FEATURE_ATOMICS) used with an invalid > > cpu_instuction_set). That means the only relevant parameter for Arm is platform > > and if we want to have a build usable on most machines of the build type, we > > have to use platform=generic. > > > > > > For x86 and ppc, there's no difference between native and generic platform (as > > it's a new argument, the purpose of which is to differentiate DPDK config across > > platforms, which doesn't exist for x86 and ppc - DPDK config is the same (correct > > me if I'm wrong)). > > > > > > So it basically boils down to what should be the default value of > > cpu_instruction_set when platform=generic (for platform=native, it's obviously > > native): > > > 1. cpu_instruction_set=native, this would preserve the current behavior, but > > we won't use the 'auto' default. I think we can fall back to this if we don't agree > > on anything better. > > > 2. cpu_instruction_set=auto, the same as cpu_instruction_set=generic, > > > 3. cpu_instruction_set=generic, this changes behavior for ppc builds, but we > > may be able to remedy this: > > > Similarly to arm (arm is using platform for this, but the idea is the same), if > > cpu_instruction_set is generic, we can do some discovery for pcc and set the ISA > > accordingly (either power8 or power9). If I understand it correctly, power8 is a > > different architecture from power9 (I could be wrong on this), so this is > > desirable. There's some logic in config/ppc/meson.build, but it doesn't seem > > sufficient as a discovery mechanism between power8/power9. > > > > POWER8 code (Power ISA v2.07) runs on POWER9 CPUs (Power ISA v3.0), so > > setting cpu_instruction_set to GENERIC is a reasonable option. POWER10 CPUs > > (Power ISA v3.1) are around the corner so I want to make sure developers can > > tune the application for the platform as easily as possible. I'm fine with > > supporting GENERIC, just need clear instructions on how to build for a particular > > ISA. > > > > That's good to hear. Setting cpu_instruction_set will set the ISA. > > We'll need to document the behavior properly, but I'm not sure where - Bruce? Seems like meson_options.txt doesn't have enough room for that. > Yes, agreed. I suggest putting in the option help text a link to the documentation where we explain the options more fully. /Bruce