From my understanding, the foreach term dictates that the compiler must create different instances to run each iteration of the code such that each iteration is running the same exact instruction. This is different than when we use launch, which spawns multiple threads and does not abide by the same restrictions as simd.
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adsmith
If you spawn multiple threads on one core, they will run concurrently rather than in true parallel. That is, only one thread will be running at any time, but the core may switch between them to hide latency. On the other hand, using SIMD still only has one instruction thread, but performs those instructions on several sets of data in parallel.
This isn't really a dichotomy; they do two different things. If you wanted, you could spawn multiple threads, each performing a different program flow of vector computations with SIMD. The processor would attempt to hide latency from (now vector-sized) memory instructions by switching between these threads.
From my understanding, the foreach term dictates that the compiler must create different instances to run each iteration of the code such that each iteration is running the same exact instruction. This is different than when we use launch, which spawns multiple threads and does not abide by the same restrictions as simd.
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If you spawn multiple threads on one core, they will run concurrently rather than in true parallel. That is, only one thread will be running at any time, but the core may switch between them to hide latency. On the other hand, using SIMD still only has one instruction thread, but performs those instructions on several sets of data in parallel.
This isn't really a dichotomy; they do two different things. If you wanted, you could spawn multiple threads, each performing a different program flow of vector computations with SIMD. The processor would attempt to hide latency from (now vector-sized) memory instructions by switching between these threads.
This comment was marked helpful 0 times.