Hello, I have a problem with make -j parallel execution in our project build.
My environment information OS: Red Hat 7.7 virtual machine with 4 CPUs lscpu Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 4 On-line CPU(s) list: 0-3 Thread(s) per core: 1 Core(s) per socket: 1 Socket(s): 4 NUMA node(s): 1 Vendor ID: GenuineIntel CPU family: 6 Model: 63 Model name: Intel(R) Xeon(R) CPU E5-2698 v3 @ 2.30GHz Stepping: 2 CPU MHz: 2297.339 BogoMIPS: 4594.67 Hypervisor vendor: VMware Virtualization type: full L1d cache: 32K L1i cache: 32K L2 cache: 256K L3 cache: 40960K NUMA node0 CPU(s): 0-3 Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc eagerfpu pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm invpcid_single ssbd ibrs ibpb stibp fsgsbase tsc_adjust bmi1 avx2 smep bmi2 invpcid xsaveopt arat md_clear spec_ctrl intel_stibp flush_l1d arch_capabilities GNU make: /opt/rh/devtoolset-9/root/usr/bin/make GNU Make 4.2.1 /usr/bin/make GNU Make 3.82 gcc/g++: /opt/rh/devtoolset-9/root/usr/bin/gcc, /opt/rh/devtoolset-9/root/usr/bin/g++ gcc version 9.1.1 20190605 (Red Hat 9.1.1-2) (GCC) If I build our project with /opt/rh/devtoolset-9/root/usr/bin/make -j 4, there is only on g++ process. In other words, -j 4 parallel execution option does not work here. The project build takes 75 minutes. [cid:image001.png@01D7F681.ABE27C80] If I build our project with /usr/bin/make -j 4, I can see 4 g++ process. The project build takes only 25 minutes. [cid:image002.png@01D7F681.ABE27C80] I checked related GNU make document. It seems no additional configuration is required for -j option. https://www.gnu.org/software/make/manual/html_node/Parallel.html I need your help to make progress in this task. Could you help to look into it? Is this a misconfiguration in my project build environment or a bug in GNU Make 4.2.1? Is there anyway to get it work? Thanks, Mason
