Symbol U_hw

The passage around this formula

…device can theoretically do from what a piece of software actually gets it to do, and splits that gap into two distinct causes: $T_{\mathrm{achieved}} = T_{\mathrm{peak}} \cdot U_{\mathrm{hw}} \cdot U_{\mathrm{compiler}}$. Here $T_{\mathrm{peak}}$ is the arithmetic identity fixed at design time, $U_{\mathrm{hw}}$ $\in$ (0,1] is the fraction of cycles the hardware keeps its arithmetic units genuinely busy on whatever workload is thrown at it, and $U_{\mathrm{compiler}}$ $\in$ (0,1] is the fraction of a program’s theoretically available parallelism that the compiler or mapper actually manages to…

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