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Starting with the "Sandy Bridge" generation, Intel CPUs provide a RAPL interface (Running Average Power Limit) for advertising the accumulated energy consumption of various power domains (e.g. CPU packages, DRAM, etc.). The consumption is reported via MSRs (model specific registers) like MSR_PKG_ENERGY_STATUS for the CPU package power domain. These MSRs are 64 bits registers that represent the accumulated energy consumption in micro Joules. They are updated by microcode every ~1ms. For now, KVM always returns 0 when the guest requests the value of these MSRs. Use the KVM MSR filtering mechanism to allow QEMU handle these MSRs dynamically in userspace. To limit the amount of system calls for every MSR call, create a new thread in QEMU that updates the "virtual" MSR values asynchronously. Each vCPU has its own vMSR to reflect the independence of vCPUs. The thread updates the vMSR values with the ratio of energy consumed of the whole physical CPU package the vCPU thread runs on and the thread's utime and stime values. All other non-vCPU threads are also taken into account. Their energy consumption is evenly distributed among all vCPUs threads running on the same physical CPU package. To overcome the problem that reading the RAPL MSR requires priviliged access, a socket communication between QEMU and the qemu-vmsr-helper is mandatory. You can specified the socket path in the parameter. This feature is activated with -accel kvm,rapl=true,path=/path/sock.sock Actual limitation: - Works only on Intel host CPU because AMD CPUs are using different MSR adresses. - Only the Package Power-Plane (MSR_PKG_ENERGY_STATUS) is reported at the moment. Signed-off-by: Anthony Harivel <aharivel@redhat.com> Link: https://lore.kernel.org/r/20240522153453.1230389-4-aharivel@redhat.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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| .. | ||
| acpi_cpu_hotplug.rst | ||
| acpi_erst.rst | ||
| acpi_hest_ghes.rst | ||
| acpi_hw_reduced_hotplug.rst | ||
| acpi_mem_hotplug.rst | ||
| acpi_nvdimm.rst | ||
| acpi_pci_hotplug.rst | ||
| edu.rst | ||
| fsi.rst | ||
| fw_cfg.rst | ||
| index.rst | ||
| ivshmem-spec.rst | ||
| pci-ids.rst | ||
| pci-serial.rst | ||
| pci-testdev.rst | ||
| ppc-spapr-hcalls.rst | ||
| ppc-spapr-hotplug.rst | ||
| ppc-spapr-numa.rst | ||
| ppc-spapr-uv-hcalls.rst | ||
| ppc-spapr-xive.rst | ||
| ppc-xive.rst | ||
| pvpanic.rst | ||
| rapl-msr.rst | ||
| rocker.txt | ||
| sev-guest-firmware.rst | ||
| standard-vga.rst | ||
| tpm.rst | ||
| virt-ctlr.rst | ||
| vmcoreinfo.rst | ||
| vmgenid.rst | ||
| vmw_pvscsi-spec.rst | ||