[v11,0/6] Add PMD power mgmt

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 (6):
  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           |  51 +++
 doc/guides/rel_notes/release_20_11.rst        |  17 +
 .../sample_app_ug/l3_forward_power_man.rst    |  14 +
 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_ethdev/rte_ethdev.c                |  23 ++
 lib/librte_ethdev/rte_ethdev.h                |  41 +++
 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 +
 21 files changed, 725 insertions(+), 3 deletions(-)
 create mode 100644 lib/librte_power/rte_power_pmd_mgmt.c
 create mode 100644 lib/librte_power/rte_power_pmd_mgmt.h