This patchset proposes a simple API for Ethernet drivers to cause the CPU to enter a power-optimized state while waiting for packets to arrive, along with a set of generic intrinsics that facilitate that. This is achieved through cooperation with the NIC driver that will allow us to know address of wake up event, and wait for writes on it.
On IA, this is achieved through using UMONITOR/UMWAIT instructions. They are used in their raw opcode form because there is no widespread compiler support for them yet. Still, the API is made generic enough to hopefully support other architectures, if they happen to implement similar instructions. To achieve power savings, there is a very simple mechanism used: we're counting empty polls, and if a certain threshold is reached, we get the address of next RX ring descriptor from the NIC driver, arm the monitoring hardware, and enter a power-optimized state. We will then wake up when either a timeout happens, or a write happens (or generally whenever CPU feels like waking up - this is platform- specific), and proceed as normal. The empty poll counter is reset whenever we actually get packets, so we only go to sleep when we know nothing is going on. The mechanism is generic which can be used for any write back descriptor. Why are we putting it into ethdev as opposed to leaving this up to the application? Our customers specifically requested a way to do it wit minimal changes to the application code. The current approach allows to just flip a switch and automatically have power savings. - Only 1:1 core to queue mapping is supported, meaning that each lcore must at most handle RX on a single queue - Support 3 type policies. UMWAIT/PAUSE/Frequency_Scale - Power management is enabled per-queue - The API doesn't extend to other device types Liang Ma (9): eal: add new x86 cpuid support for WAITPKG eal: add power management intrinsics eal: add intrinsics support check infrastructure ethdev: add simple power management API power: add PMD power management API and callback net/ixgbe: implement power management API net/i40e: implement power management API net/ice: implement power management API examples/l3fwd-power: enable PMD power mgmt doc/guides/prog_guide/power_man.rst | 48 +++ doc/guides/rel_notes/release_20_11.rst | 15 + .../sample_app_ug/l3_forward_power_man.rst | 13 + drivers/net/i40e/i40e_ethdev.c | 1 + drivers/net/i40e/i40e_rxtx.c | 26 ++ drivers/net/i40e/i40e_rxtx.h | 2 + drivers/net/ice/ice_ethdev.c | 1 + drivers/net/ice/ice_rxtx.c | 26 ++ drivers/net/ice/ice_rxtx.h | 2 + drivers/net/ixgbe/ixgbe_ethdev.c | 1 + drivers/net/ixgbe/ixgbe_rxtx.c | 25 ++ drivers/net/ixgbe/ixgbe_rxtx.h | 2 + examples/l3fwd-power/main.c | 46 ++- lib/librte_eal/arm/include/meson.build | 1 + .../arm/include/rte_power_intrinsics.h | 60 ++++ lib/librte_eal/arm/rte_cpuflags.c | 6 + lib/librte_eal/include/generic/rte_cpuflags.h | 26 ++ .../include/generic/rte_power_intrinsics.h | 123 +++++++ lib/librte_eal/include/meson.build | 1 + lib/librte_eal/ppc/include/meson.build | 1 + .../ppc/include/rte_power_intrinsics.h | 60 ++++ lib/librte_eal/ppc/rte_cpuflags.c | 7 + lib/librte_eal/version.map | 1 + lib/librte_eal/x86/include/meson.build | 1 + lib/librte_eal/x86/include/rte_cpuflags.h | 1 + .../x86/include/rte_power_intrinsics.h | 135 ++++++++ lib/librte_eal/x86/rte_cpuflags.c | 14 + lib/librte_ethdev/rte_ethdev.c | 23 ++ lib/librte_ethdev/rte_ethdev.h | 33 ++ lib/librte_ethdev/rte_ethdev_driver.h | 28 ++ lib/librte_ethdev/version.map | 1 + lib/librte_power/meson.build | 5 +- lib/librte_power/rte_power_pmd_mgmt.c | 320 ++++++++++++++++++ lib/librte_power/rte_power_pmd_mgmt.h | 92 +++++ lib/librte_power/version.map | 4 + 35 files changed, 1148 insertions(+), 3 deletions(-) create mode 100644 lib/librte_eal/arm/include/rte_power_intrinsics.h create mode 100644 lib/librte_eal/include/generic/rte_power_intrinsics.h create mode 100644 lib/librte_eal/ppc/include/rte_power_intrinsics.h create mode 100644 lib/librte_eal/x86/include/rte_power_intrinsics.h create mode 100644 lib/librte_power/rte_power_pmd_mgmt.c create mode 100644 lib/librte_power/rte_power_pmd_mgmt.h -- 2.17.1
