[next-queue,v4,0/4] Add an i40e_napi_poll tracepoint

Message

Joe Damato Oct. 7, 2022, 9:38 p.m. UTC

Greetings:

Welcome to v4.

Debugging and tuning the NAPI and i40e NIC parameters can be a bit tricky
as there are many different options to test.

This change adds a tracepoint to i40e_napi_poll which exposes a lot of
helpful debug information for users who'd like to get a better
understanding of how their NIC is performing as they adjust various
parameters and tuning knobs.

Note: this series does not touch any XDP related code paths. This
tracepoint will only work when not using XDP. Care has been taken to avoid
changing control flow in i40e_napi_poll with this change.

With this series applied, you can use the tracepoint with perf (assuming
XDP is not being used) by running:

$ sudo perf trace -e i40e:i40e_napi_poll -a --call-graph=fp --libtraceevent_print

388.258 :0/0 i40e:i40e_napi_poll(i40e_napi_poll on dev eth2 q i40e-eth2-TxRx-9 irq 346 irq_mask 00000000,00000000,00000000,00000000,00000000,00800000 curr_cpu 23 budget 64 bpr 64 rx_cleaned 28 tx_cleaned 0 rx_clean_complete 1 tx_clean_complete 1)
	i40e_napi_poll ([i40e])
	i40e_napi_poll ([i40e])
	__napi_poll ([kernel.kallsyms])
	net_rx_action ([kernel.kallsyms])
	__do_softirq ([kernel.kallsyms])
	common_interrupt ([kernel.kallsyms])
	asm_common_interrupt ([kernel.kallsyms])
	intel_idle_irq ([kernel.kallsyms])
	cpuidle_enter_state ([kernel.kallsyms])
	cpuidle_enter ([kernel.kallsyms])
	do_idle ([kernel.kallsyms])
	cpu_startup_entry ([kernel.kallsyms])
	[0x243fd8] ([kernel.kallsyms])
	secondary_startup_64_no_verify ([kernel.kallsyms])

The output is verbose, but is helpful when trying to determine the impact of
various turning parameters.

Thanks,
Joe

v3 -> v4:
	- All XDP related changes were dropped from both the TX and RX
	  paths (patches 2/4 and 3/4 were updated).
	- A conditional was added to only fire the tracepoint if XDP is NOT
	  enabled (patch 4/4 updated).
	- Fixed format specifier for rx_cleaned and tx_cleaned (from %lu
	  to %u in patch 4/4).

v2 -> v3:
	- Add an rx_clean_complete to the RX patch so that it can be output
	  in tracepoint instead of the valued of 'clean_complete' which can
	  be ambiguous (patch 3/4 was updated).
	- Update the tracepoint to swap 'clean_complete' with
	  'rx_clean_complete' (patch 4/4 was updated).

v1 -> v2:
	- TX path modified to push an out parameter through the function
	  call chain instead of modifying control flow.
	- RX path modified to also use an out parameter to track the number
	  of packets processed.
	- Naming of tracepoint struct members and format string modified to
	  be more readable.

Thanks,
Joe

Joe Damato (4):
  i40e: Store the irq number in i40e_q_vector
  i40e: Record number TXes cleaned during NAPI
  i40e: Record number of RXes cleaned during NAPI
  i40e: Add i40e_napi_poll tracepoint

 drivers/net/ethernet/intel/i40e/i40e.h       |  1 +
 drivers/net/ethernet/intel/i40e/i40e_main.c  |  1 +
 drivers/net/ethernet/intel/i40e/i40e_trace.h | 49 ++++++++++++++++++++++++++++
 drivers/net/ethernet/intel/i40e/i40e_txrx.c  | 27 +++++++++++----
 4 files changed, 72 insertions(+), 6 deletions(-)