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d="scan'208";a="442556292" Received: from bricha3-mobl.ger.corp.intel.com ([10.252.17.64]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-SHA; 25 Feb 2021 04:54:27 -0800 Date: Thu, 25 Feb 2021 12:54:23 +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: <20210225125423.GC1546@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> <20210223094300.GA79@bricha3-MOBL.ger.corp.intel.com> <93f1a074bcc24de18ae0423a217ed817@pantheon.tech> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <93f1a074bcc24de18ae0423a217ed817@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 Thu, Feb 25, 2021 at 12:51:57PM +0000, Juraj Linkeš wrote: > > > > -----Original Message----- > > From: Bruce Richardson > > Sent: Tuesday, February 23, 2021 10:43 AM > > To: Juraj Linkeš > > Cc: David Christensen ; thomas@monjalon.net; > > Honnappa.Nagarahalli@arm.com; dev@dpdk.org > > Subject: Re: [RFC PATCH v2] build: add platform meson option > > > > 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 > > You mentioned in the kni cross compile patch that we should do a separate patch where we explain the option in docs and I believe this would go into that patch. Before we do that, let's figure out the best description without the link. I currently have: > option('cpu_instruction_set', type: 'string', value: 'auto', > description: 'Set the target machine ISA (instruction set architecture). Will be set according to the platform option by default.') > option('platform', type: 'string', value: 'generic', > description: 'Platform to build, either "native" or "generic".') > > What do you think? Should we expand the platform description a bit? Are there not more platform options than just those two?