3 ms·
It seems like you can only make this mistake if you assume that Intel CPUs always use the frequency from the CPUID name for timer ticks, which seems like a dang
by cmeacham98 6y ago
It seems like you can only make this mistake if you assume that Intel CPUs always use the frequency from the CPUID name for timer ticks, which seems like a dangerous assumption even today (I'd love to see someone test this on a CPU with an overclocked BCLK).
- scaramanga 6y agoAs far as I can tell it is false: model name : Intel(R) Core(TM) i7-6600U CPU @ 2.60GHz cpu MHz : 2600.028 But tsc clock freq according to max non-turbo ration reported by MSR 0xce is 28 (* 100MHz) = 2.8GHz As I understand it, tsc ticks at a constant rate according to this value.
- jfrunyon 6y agoIndeed it seems a dangerous assumption, considering the Intel Software Developer's Manual explicitly says it's not true... > For [big list of models]: the time-stamp counter increments at a constant rate. That rate may be set by the maximum core-clock to bus-clock ratio of the processor or may be set by the maximum resolved frequency at which the processor is booted. The maximum resolved frequency may differ from the processor base frequency, see Section 18.7.2 for more detail. On certain processors, the TSC frequency may not be the same as the frequency in the brand string. (Vol 3B § 17.17 / PDF page 3443 https://software.intel.com/content/www/us/en/develop/articles/intel-sdm.html https://software.intel.com/content/www/us/en/develop/article...)