[PATCH iwl-next v2 0/4] ixgbe: adaptive ITR tuning for RX starvation and latency workloads

[Aleksandr Loktionov <aleksandr.loktionov@intel.com>]

This is v2 of the ixgbe adaptive ITR tuning patchset for iwl-next.

v2 changes:
 - No code changes. Resending to pick up Reviewed-by: Simon Horman
   on patches 1 and 2 (patches 3 and 4 already carried it).

This series tunes the adaptive interrupt-throttle-rate (ITR) algorithm
in ixgbe_update_itr():

- Lower IXGBE_ITR_ADAPTIVE_MAX_USECS from 126 to 84 us so the minimum
  bulk-mode interrupt rate is high enough to avoid descriptor ring
  starvation under sustained full-line-rate RX traffic.

- Add an ixgbe_container_is_rx() helper and refine the RX-specific
  latency-detection thresholds for finer-grained control over
  low-rate RX latency workloads without affecting TX.

- Limit how far a single ITR update can lower the interrupt rate while
  in latency mode, so a low-packet-rate ACK-only workload cannot drive
  the moderation down too aggressively in one step.

- Add an IXGBE_ITR_ADAPTIVE_MASK_USECS constant to replace an
  open-coded complement expression with an explicit named mask.

A fifth patch from the same original batch, removing a redundant
ixgbe_ping_all_vfs() call from the link watchdog handlers, addresses an
unrelated VF mailbox race rather than ITR/RX-starvation behavior and is
sent separately so this series stays focused on one topic.

Alexander Duyck (4):
  ixgbe: lower IXGBE_ITR_ADAPTIVE_MAX_USECS to prevent RX starvation
  ixgbe: add ixgbe_container_is_rx() helper and refine RX adaptive ITR
  ixgbe: limit ITR decrease in latency mode to prevent ACK overdrive
  ixgbe: add IXGBE_ITR_ADAPTIVE_MASK_USECS constant

 drivers/net/ethernet/intel/ixgbe/ixgbe.h      |  3 +-
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 80 +++++++++++--------
 2 files changed, 49 insertions(+), 34 deletions(-)

-- 
2.52.0