[dpdk-dev] [PATCH v4 3/6] build: optional NUMA and cpu counts detection

[Juraj Linkeš]

Add an option to automatically discover the host's numa and cpu counts
and use those values for a non cross-build.
Give users the option to override the per-arch default values or values
from cross files by specifying them on the command line with -Dmax_lcores
and -Dmax_numa_nodes.

Signed-off-by: Juraj Linkeš <juraj.linkes at pantheon.tech>
---
 buildtools/get_cpu_count.py  |  7 ++++++
 buildtools/get_numa_count.py | 22 +++++++++++++++++
 buildtools/meson.build       |  2 ++
 config/meson.build           | 48 ++++++++++++++++++++++++++++++++++--
 meson_options.txt            |  8 +++---
 5 files changed, 81 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..f0c49973a
--- /dev/null
+++ b/buildtools/get_numa_count.py
@@ -0,0 +1,22 @@
+#!/usr/bin/python3
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2020 PANTHEON.tech s.r.o.
+
+import ctypes
+import glob
+import os
+import subprocess
+
+if os.name == 'posix':
+    if os.path.isdir('/sys/devices/system/node'):
+        print(len(glob.glob('/sys/devices/system/node/node*')))
+    else:
+        print(subprocess.run(['sysctl', 'vm.ndomains'], capture_output=True).stdout)
+
+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 918ca2dfb..5c6fdcc7d 100644
--- a/config/meson.build
+++ b/config/meson.build
@@ -230,8 +230,14 @@ 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'))
+if not meson.is_cross_build()
+	# set default values
+	# these defaults may be overwritten by meson.build in an arch subdir
+	# or later overwritten if a user specifies a value on the command line
+	# or the user chooses to use values discovered from the build machine
+	dpdk_conf.set('RTE_MAX_LCORE', 128)
+	dpdk_conf.set('RTE_MAX_NUMA_NODES', 4)
+endif
 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'))
@@ -250,6 +256,44 @@ compile_time_cpuflags = []
 subdir(arch_subdir)
 dpdk_conf.set('RTE_COMPILE_TIME_CPUFLAGS', ','.join(compile_time_cpuflags))
 
+max_lcores = get_option('max_lcores')
+max_numa_nodes = get_option('max_numa_nodes')
+if max_lcores > 0
+	dpdk_conf.set('RTE_MAX_LCORE', max_lcores)
+elif max_lcores == -1
+	if not meson.is_cross_build()
+		max_lcores = run_command(get_cpu_count_cmd).stdout().to_int()
+		min_lcores = 2
+		if max_lcores < min_lcores
+			message('Found less than @0@ cores, building for @0@ cores'.format(min_lcores))
+			max_lcores = min_lcores
+		else
+			message('Found @0@ cores'.format(max_lcores))
+		endif
+		dpdk_conf.set('RTE_MAX_LCORE', max_lcores)
+	endif
+endif
+
+if max_numa_nodes > 0
+	dpdk_conf.set('RTE_MAX_NUMA_NODES', max_numa_nodes)
+elif max_numa_nodes == -1
+	if not meson.is_cross_build()
+		max_numa_nodes = run_command(get_numa_count_cmd).stdout().to_int()
+		message('Found @0@ numa nodes'.format(max_numa_nodes))
+		dpdk_conf.set('RTE_MAX_NUMA_NODES', max_numa_nodes)
+	endif
+endif
+
+# check that cpu and numa count is set in cross builds
+if meson.is_cross_build()
+	if not dpdk_conf.has('RTE_MAX_LCORE')
+		error('Number of cores for cross build not specified in @0@ subdir (e.g. in a cross-file) nor on the cmdline'.format(arch_subdir))
+	endif
+	if not dpdk_conf.has('RTE_MAX_NUMA_NODES')
+		error('Number of numa nodes for cross build not specified in @0@ subdir (e.g. in a cross-file) nor on the cmdline'.format(arch_subdir))
+	endif
+endif
+
 # set the install path for the drivers
 dpdk_conf.set_quoted('RTE_EAL_PMD_PATH', eal_pmd_path)
 
diff --git a/meson_options.txt b/meson_options.txt
index 9bf18ab6b..a78c21b0d 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. Set to positive integer to overwrite per-arch or cross-compilation defaults. Set to -1 to use number of cores on the build machine.')
+option('max_numa_nodes', type: 'integer', value: 0,
+	description: 'maximum number of NUMA nodes supported by EAL. Set to positive integer to overwrite per-arch or cross-compilation defaults. Set to -1 to use number of numa nodes on the build machine.')
 option('enable_trace_fp', type: 'boolean', value: false,
 	description: 'enable fast path trace points.')
 option('tests', type: 'boolean', value: true,
-- 
2.20.1