> Hello, > > the problem is that turbo can be enabled/disabled by the firmware at runtime, > after the machine has booted. > > This happens for example with the Dell XPS 13, where turbo gets disabled by > the firmware if the machine is disconnected from AC power and runs on battery. > The laptop could boot on battery (turbo disabled), then after some time the > user connects the AC power supply, turbo gets enabled, and with your patch > we wouldn't know what is the turbo_freq/base_freq ratio to do frequency > invariance (we skipped reading MSR_TURBO_RATIO_LIMIT at boot because > turbo was disabled at that timed). > > This behavior was requested by reviewers in this thread: > https://lore.kernel.org/lkml/1906426.HDqaVa71mF@kreacher/ > and implemented with 918229cdd5ab ("x86/intel_pstate: Handle runtime turbo > disablement/enablement in frequency invariance"). >
Thanks for you explanation Sorry for noise -Li > > Thanks, > Giovanni Gherdovich