docs/specs/rapl-msr.rst

5 The RAPL interface (Running Average Power Limit) is advertising the accumulated
6 energy consumption of various power domains (e.g. CPU packages, DRAM, etc.).
9 MSR_PKG_ENERGY_STATUS for the CPU package power domain. These MSRs are 64 bits
12 Thanks to KVM's `MSR filtering <msr-filter-patch_>`__ functionality,
17 .. _msr-filter-patch: https://patchwork.kernel.org/project/kvm/patch/20200916202951.23760-7-graf@am…
29 spec and specify the power limit of the package, provide range of parameter(min
30 power, max power,..) and also the information of the multiplier for the energy
31 counter to calculate the power. Those MSRs are populated once at the beginning
37 it with the UNIT provided above you'll get the power in micro-joules. This
45 core that belongs to PKG-0 will not be able to get the value of PKG-1 and
46 vice-versa.
49 -------------------------
60 3. Sleep for 1 second - During this pause the vcpu and other non-vcpu threads
67 5. Filter the vcpu threads and the non-vcpu threads.
72 7. The total energy spent by the non-vcpu threads is divided by the number
87 -----------------
101 .. _stat: https://man7.org/linux/man-pages/man5/proc.5.html
116 -----
119 mounted and available in the sysfs. if not, QEMU fails at start-up.
121 This feature is activated with -accel
122 kvm,rapl=true,rapl-helper-socket=/path/sock.sock
125 :program:`qemu-vmsr-helper` is listening to.
127 qemu-vmsr-helper
128 ----------------
130 The qemu-vmsr-helper is working very much like the qemu-pr-helper. Instead of
131 making persistent reservation, qemu-vmsr-helper is here to overcome the
132 CVE-2020-8694 which remove user access to the rapl msr attributes.
135 MSR support activated and the qemu-vmsr-helper. A systemd service and socket
136 activation is provided in contrib/systemd/qemu-vmsr-helper.(service/socket).
138 The systemd socket uses 600, like contrib/systemd/qemu-pr-helper.socket. The
144 See the qemu-pr-helper documentation or manpage for further details.
147 -------------------
149 - Works only on Intel host CPUs because AMD CPUs are using different MSR
152 - Only the Package Power-Plane (MSR_PKG_ENERGY_STATUS) is reported at the