aarch64 cycle count with frequency #179
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AArch64 CPU may using off-core timer as source of
cntvct_el0registers, so the counter may not fit CPU working frequency. The timer frequency on Apple M1 is 24MHz, much lower than CPU working frequency, that may makephoton::nowtimestamp update about every 40ms, may makes photon thread sleeps longer than it should be.The fix uses
cntvct_el0as a fast check whether should update time stamp, calculate withcntfrq_el0as timer frequency, make it able to update timestamp as it designed to.