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→Interrupt latency
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When dynamic processor's voltage/frequency scaling is enabled, Linux kernel performs a lot of transactions between different [[FAQs_(Axel)#Q:_How_can_I_change_the_CPU_clock_frequency.3F|OPPs]]. Two approaches are available to implement such transactions:
* PMIC-based: in this case an external Power Management Integrated Circuit (PMIC) is used to change the processor's voltages
* internal LDOs-based: in this case processor's internal linear regulators are used to change such voltages.
PMIC is connected to the processor via I2C bus. As such, every time a transaction is needed, several I2C packets need to be trasnmitted transmitted over I2C bus, resulting in a relatively slow overall transaction time. In case LDOs-based approach is adopted instead, transaction transactions are quicker because LDOs configuration registers are directly accessible in the processor's address space. On the other hand, the use of LDOs has a significant drawback as explained in the following section.
==Processor heating and lifetime==
