[Intel-wired-lan] [PATCH net-next v3 1/3] ice: update dim usage and moderation

[Jesse Brandeburg <jesse.brandeburg@intel.com>]

On 9/19/2021 11:46 PM, Paul Menzel wrote:
> Dear Jesse,

Thanks for reviewing, I applied your text changes to v4.

> Am 24.08.21 um 03:12 schrieb Jesse Brandeburg:
>> Add a new helper for setting rate limit, which will be used more
>> in a followup patch.
> 
> Nice work. Could you please add, how to run the ping-pong test, so
> others can verify the behavior?

The test ran 32 rounds of netperf -t TCP_RR with a single thread, with
sizes of bytes transferred varying in powers of two from 1-64K.
each command was something like (for example for the 8K ping pong)
netperf -t TCP_RR -H host -l 30 -- -r 8K


>> @@ -1328,15 +1345,14 @@ static u32 ice_buildreg_itr(u16 itr_idx, u16 itr)
>> ? }
>> ? ? /**
>> - * ice_update_ena_itr - Update ITR moderation and re-enable MSI-X
>> interrupt
>> + * ice_enable_interrupt - re-enable MSI-X interrupt
>> ?? * @q_vector: the vector associated with the interrupt to enable
>> ?? *
>> - * Update the net_dim() algorithm and re-enable the interrupt
>> associated with
>> - * this vector.
>> - *
>> - * If the VSI is down, the interrupt will not be re-enabled.
>> + * If the VSI is down, the interrupt will not be re-enabled. Also,
>> + * when enabling the interrupt always reset the wb_on_itr to false
>> + * and trigger a software interrupt to clean out internal state.
> 
> Is the internal state cleaning required in the spec?

It is mentioned in the interrupt management section that triggering a
software interrupt will "flush" internal state. The spec just doesn't
mention when you should use that trick.