Control: tags -1 - moreinfo Hi Andrew,
On Fri, Jan 10, 2025 at 09:00:50AM -0800, Andrew Jorgensen wrote: > Hi Salvatore, > > One of my colleagues supplied this explanation: > > ""' > intel_idle is a kernel module that implements specialized logic for > handling CPU idle/sleep states. This logic is optimized for Intel CPUs > to achieve better results than what is possible through the ACPI > C-state mechanism. For example, intel_idle can specify C-state target > residency different than 2*latency. Better results here means lower > wakeup latency (vs ACPI) while not compromising performance and power > savings. Without intel_idle, many VMs will use HLT for putting the CPU > cores to sleep, which will only put Intel CPUs in a shallow sleep > state, thus wasting power that could otherwise be saved or used by > other cores by boosting higher. > > Importantly, intel_idle requires the presence of MWAIT instruction. > For some time, this hasn't been available in virtualized environments, > but it is now relatively widespread: > - GCE: https://cloud.google.com/compute/docs/cpu-platforms#frequency_behavior > - AWS: > https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/processor_state_control.html > > Note this module is already present and used in many other cloud > distro images: Ubuntu, CentOS, RHEL, Rocky, CentOS to name a few. > """ > > So in summary, the benefits to the Debian cloud kernel user are lower > wakeup latency and the ability to boost other cores higher by putting > some cores into a deeper sleep state (making power and thermal budget > available to adjacent cores). Many thanks for providing the more info. We are going to enable intel_idle for the cloud kernel then. Regards, Salvatore
