Critical range specifies a margin of delay for path groups in optimization. This must be a positive float number or 0.0. A critical rangeof 0.0 means that only the most critical paths (the ones with the worst violation) are optimized. If you specify a nonzero critical range,
near-critical paths within that amount of the worst path will also be optimized, if possible.
明白了,下午没好好看,就没有看懂……