[dpdk-dev] [PATCH v12 00/11] Add PMD power management

[Anatoly Burakov]

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. 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.

This patchset also introduces a few changes into existing power 
management-related intrinsics, namely to provide a native way of waking 
up a sleeping core without application being responsible for it, as well 
as general robustness improvements. There's quite a bit of locking going 
on, but these locks are per-thread and very little (if any) contention 
is expected, so the performance impact shouldn't be that bad (and in any 
case the locking happens when we're about to sleep anyway, not on a 
hotpath).

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. Monitor/Pause/Frequency Scaling
- Power management is enabled per-queue
- The API doesn't extend to other device types

Anatoly Burakov (5):
  eal: uninline power intrinsics
  eal: avoid invalid API usage in power intrinsics
  eal: change API of power intrinsics
  eal: remove sync version of power monitor
  eal: add monitor wakeup function

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           |  44 +++
 doc/guides/rel_notes/release_21_02.rst        |  14 +
 .../sample_app_ug/l3_forward_power_man.rst    |  35 ++
 drivers/event/dlb/dlb.c                       |  10 +-
 drivers/event/dlb2/dlb2.c                     |  10 +-
 drivers/net/i40e/i40e_ethdev.c                |   1 +
 drivers/net/i40e/i40e_rxtx.c                  |  25 ++
 drivers/net/i40e/i40e_rxtx.h                  |   1 +
 drivers/net/ice/ice_ethdev.c                  |   1 +
 drivers/net/ice/ice_rxtx.c                    |  26 ++
 drivers/net/ice/ice_rxtx.h                    |   1 +
 drivers/net/ixgbe/ixgbe_ethdev.c              |   1 +
 drivers/net/ixgbe/ixgbe_rxtx.c                |  25 ++
 drivers/net/ixgbe/ixgbe_rxtx.h                |   1 +
 examples/l3fwd-power/main.c                   |  89 ++++-
 .../arm/include/rte_power_intrinsics.h        |  39 +-
 .../include/generic/rte_power_intrinsics.h    |  78 ++--
 .../ppc/include/rte_power_intrinsics.h        |  39 +-
 lib/librte_eal/version.map                    |   5 +
 .../x86/include/rte_power_intrinsics.h        | 115 ------
 lib/librte_eal/x86/meson.build                |   1 +
 lib/librte_eal/x86/rte_power_intrinsics.c     | 169 +++++++++
 lib/librte_ethdev/rte_ethdev.c                |  28 ++
 lib/librte_ethdev/rte_ethdev.h                |  25 ++
 lib/librte_ethdev/rte_ethdev_driver.h         |  22 ++
 lib/librte_ethdev/version.map                 |   3 +
 lib/librte_power/meson.build                  |   5 +-
 lib/librte_power/rte_power_pmd_mgmt.c         | 349 ++++++++++++++++++
 lib/librte_power/rte_power_pmd_mgmt.h         |  90 +++++
 lib/librte_power/version.map                  |   5 +
 30 files changed, 1028 insertions(+), 229 deletions(-)
 create mode 100644 lib/librte_eal/x86/rte_power_intrinsics.c
 create mode 100644 lib/librte_power/rte_power_pmd_mgmt.c
 create mode 100644 lib/librte_power/rte_power_pmd_mgmt.h

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2.17.1