So many different terms have been introduced so the chances of confusion are high, but per my understanding, the word "instruction stream" isn't the right word here. An instruction stream is at the level of the entire core. The core processes the instruction stream, and in turn, it sends individual instructions to threads, each of which will manage its assigned instructions using its own execution context. When there is a stall, the processor can switch to another thread's execution, which would be another part of the same overall instruction stream. Is this correct?

I'm referring to the sentence "But can switch to processing the other instruction stream when faced with a stall."

one instruction stream corresponds to one core, while one thread corresponds to one execution context

@donquixote I found what you said quite helpful. I agree with you on this slide. Hardware multithreading as we talked about in class does not refer to switching between instruction streams/cores, only between different execution contexts/threads on the same core.

@donquixote I was also a bit confused with all of the new vocab. Something that helped me was understanding the difference between the three words: parallelism, simultaneity, and multithreading. In my mind I assumed these words were synonyms but after OH I realized this is not the case. Parallelism is an umbrella term that encapsulated multiple techniques. In this example above we DO see multithreading due to the fact each processor has has 2 Execution Contexts. However we Do NOT see simultaneity since two threads are not able to execute at the same time since there is only 1 Fetch/Decode block on each processor.

I am having problem relating all the new vocabs as well. For this slides in particular, I originally thought SIMD is something that happen on a single core. But in this slides, does illustration on the right side mean four cores? Or just 1 core that is capable to executing 4 instructions in parallel?