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I'm trying to understand how clock_gettime works and I'm uncertain as to how scaled CPU frequencies are handled. If I look at the clock_gettime code it calls a function call get_clockfreq. This patterns is the same in multiple versions of this code. On linux this frequency is read once from the '/proc/cpuinfo' file. This information I believe is set only once at system startup. However, during operations the actual frequency will change. I can indeed get it to have any number of values in the cpuinfo file. How does clock_gettime actually resolve this issue? Does the TSC somehow automatically represent clock-cycles in this listed frequency? Also, I noticed a 4096 buffer in get_clockfreq which reads the timer. There is a counter which says proc won't produce larger files, yet I have system where the 'cpuinfo' file is clearly larger than this. I'm sure the first 4K will have a speed in it, but the speed does not need to be the same across all CPUs. Note: I'm looking at the x86_64 code for Linux. -- edA-qa mort-ora-y -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Sign: Please digitally sign your emails. Encrypt: I'm also happy to receive encrypted mail.
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