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

[Juraj Linkeš]

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*')))
+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
+	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
+	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