[dpdk-dev] [RFC PATCH v2 3/6] build: automatic NUMA and cpu counts detection

[Bruce Richardson]

On Tue, Oct 13, 2020 at 04:54:39PM +0200, Juraj Linkeš wrote:
> The build machine's number of cpus and numa nodes vary, resulting in
> mismatched counts of RTE_MAX_LCORE and RTE_MAX_NUMA_NODES for many
> builds. Automatically discover the host's numa and cpu counts to remove
> this mismatch for native builds. Use current defaults for cross builds.
> Leave users the option to override both if the specify a non-zero
> amount on the command line.
> 
> Signed-off-by: Juraj Linkeš <juraj.linkes at pantheon.tech>
> ---
>  buildtools/get_cpu_count.py  |  7 +++++++
>  buildtools/get_numa_count.py | 17 +++++++++++++++++
>  buildtools/meson.build       |  2 ++
>  config/meson.build           | 20 ++++++++++++++++++--
>  meson_options.txt            |  8 ++++----
>  5 files changed, 48 insertions(+), 6 deletions(-)
>  create mode 100644 buildtools/get_cpu_count.py
>  create mode 100644 buildtools/get_numa_count.py
> 
> diff --git a/buildtools/get_cpu_count.py b/buildtools/get_cpu_count.py
> new file mode 100644
> index 000000000..386f85f8b
> --- /dev/null
> +++ b/buildtools/get_cpu_count.py
> @@ -0,0 +1,7 @@
> +#!/usr/bin/python3
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright (c) 2020 PANTHEON.tech s.r.o.
> +
> +import os
> +
> +print(os.cpu_count())
> diff --git a/buildtools/get_numa_count.py b/buildtools/get_numa_count.py
> new file mode 100644
> index 000000000..f2ad35532
> --- /dev/null
> +++ b/buildtools/get_numa_count.py
> @@ -0,0 +1,17 @@
> +#!/usr/bin/python3
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright (c) 2020 PANTHEON.tech s.r.o.
> +
> +import ctypes
> +import glob
> +import os
> +
> +if os.name == 'posix':
> +    print(len(glob.glob('/sys/devices/system/node/node*')))

FreeBSD also reports it's os.name as posix, but doesn't have a /sys/devices
path to query.

> +elif os.name == 'nt':
> +    libkernel32 = ctypes.windll.kernel32
> +
> +    count = ctypes.c_ulong()
> +
> +    libkernel32.GetNumaHighestNodeNumber(ctypes.pointer(count))
> +    print(count.value + 1)
> diff --git a/buildtools/meson.build b/buildtools/meson.build
> index 04808dabc..925e733b1 100644
> --- a/buildtools/meson.build
> +++ b/buildtools/meson.build
> @@ -17,3 +17,5 @@ else
>  endif
>  map_to_win_cmd = py3 + files('map_to_win.py')
>  sphinx_wrapper = py3 + files('call-sphinx-build.py')
> +get_cpu_count_cmd = py3 + files('get_cpu_count.py')
> +get_numa_count_cmd = py3 + files('get_numa_count.py')
> diff --git a/config/meson.build b/config/meson.build
> index 4bd65d98e..84c31c8e7 100644
> --- a/config/meson.build
> +++ b/config/meson.build
> @@ -226,8 +226,24 @@ foreach arg: warning_flags
>  endforeach
>  
>  # set other values pulled from the build options
> -dpdk_conf.set('RTE_MAX_LCORE', get_option('max_lcores'))
> -dpdk_conf.set('RTE_MAX_NUMA_NODES', get_option('max_numa_nodes'))
> +max_lcores = get_option('max_lcores')
> +if max_lcores == 0
> +	if meson.is_cross_build()
> +		max_lcores = 4

This seems a rather low number to default to. I would suspect in this case
you might be better just to error out, i.e. require that the max_lcores
value is given when cross-compiling.

> +	else
> +		max_lcores = run_command(get_cpu_count_cmd).stdout()
> +	endif
> +endif
> +dpdk_conf.set('RTE_MAX_LCORE', max_lcores)
> +max_numa_nodes = get_option('max_numa_nodes')
> +if max_numa_nodes == 0
> +	if meson.is_cross_build()
> +		max_numa_nodes = 128

Same here, I think it's better to force the user to specify a value.
BTW: did you unintentionally switch the max cores and max numa nodes values
in this patch?

> +	else
> +		max_numa_nodes = run_command(get_numa_count_cmd).stdout()
> +	endif
> +endif
> +dpdk_conf.set('RTE_MAX_NUMA_NODES', max_numa_nodes)
>  dpdk_conf.set('RTE_MAX_ETHPORTS', get_option('max_ethports'))
>  dpdk_conf.set('RTE_LIBEAL_USE_HPET', get_option('use_hpet'))
>  dpdk_conf.set('RTE_ENABLE_TRACE_FP', get_option('enable_trace_fp'))
> diff --git a/meson_options.txt b/meson_options.txt
> index 9bf18ab6b..60a949fca 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -26,10 +26,10 @@ option('machine', type: 'string', value: 'native',
>  	description: 'set the target machine type')
>  option('max_ethports', type: 'integer', value: 32,
>  	description: 'maximum number of Ethernet devices')
> -option('max_lcores', type: 'integer', value: 128,
> -	description: 'maximum number of cores/threads supported by EAL')
> -option('max_numa_nodes', type: 'integer', value: 4,
> -	description: 'maximum number of NUMA nodes supported by EAL')
> +option('max_lcores', type: 'integer', value: 0,
> +	description: 'maximum number of cores/threads supported by EAL. Value 0 means the number of cpus on the host will be used')
> +option('max_numa_nodes', type: 'integer', value: 0,
> +	description: 'maximum number of NUMA nodes supported by EAL. Value 0 means the number of numa nodes on the host will be used')
>  option('enable_trace_fp', type: 'boolean', value: false,
>  	description: 'enable fast path trace points.')
>  option('tests', type: 'boolean', value: true,
> -- 
> 2.20.1
>