Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 24 Mar 2023 08:55:44 -0700 | Subject | Re: [QUESTION] The delay between sampling for CPPC | From | Yang Shi <> |
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Gently ping...
On 3/20/23 10:21 AM, Yang Shi wrote: > Hi folks, > > When testing CPPC cpufreq on our platform, we noticed the error may be > quite high and it (high error) may happen quite often. For example, > our platform max freq is 2.8GHz, when the CPUs were fully loaded (100% > load), we saw cpuinfo_cur_freq may show 4GHz, it means > 40% error. > And the high error (> 1%) happened 256 times out of 2127 samples > (sampled every 3 seconds) in 2hrs test. > > We tried to change the delay to 100us, things got improved although we > still saw high error, but it happened much less often (22 times out of > 3623 samples). > > So why was 2us used as the delay? Does it make sense to use a larger > delay, for example, 100us used by our test, or even larger, for > example, ms granularity? > > Thanks, > Yang
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