Alexandre Ganea 61ed3dc5bf [ThinLTO] Allow usage of all hardware threads in the system ... Before this patch, it wasn't possible to extend the ThinLTO threads to all SMT/CMT threads in the system. Only one thread per core was allowed, instructed by usage of llvm::heavyweight_hardware_concurrency() in the ThinLTO code. Any number passed to the LLD flag /opt:lldltojobs=..., or any other ThinLTO-specific flag, was previously interpreted in the context of llvm::heavyweight_hardware_concurrency(), which means SMT disabled. One can now say in LLD: /opt:lldltojobs=0 -- Use one std::thread / hardware core in the system (no SMT). Default value if flag not specified. /opt:lldltojobs=N -- Limit usage to N threads, regardless of usage of heavyweight_hardware_concurrency(). /opt:lldltojobs=all -- Use all hardware threads in the system. Equivalent to /opt:lldltojobs=$(nproc) on Linux and /opt:lldltojobs=%NUMBER_OF_PROCESSORS% on Windows. When an affinity mask is set for the process, threads will be created only for the cores selected by the mask. When N > number-of-hardware-threads-in-the-system, the threads in the thread pool will be dispatched equally on all CPU sockets (tested only on Windows). When N <= number-of-hardware-threads-on-a-CPU-socket, the threads will remain on the CPU socket where the process started (only on Windows). Differential Revision: https://reviews.llvm.org/D75153		2020-03-27 10:20:58 -04:00
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CMakeLists.txt
llvm-lto2.cpp	[ThinLTO] Allow usage of all hardware threads in the system	2020-03-27 10:20:58 -04:00
LLVMBuild.txt