On 09/21/2018 12:17 AM, Song Liu wrote:
>
>
>> On Sep 20, 2018, at 4:49 PM, Eric Dumazet <eric.duma...@gmail.com> wrote:
>>
>>
>>
>> On 09/20/2018 04:43 PM, Song Liu wrote:
>>>
>>
>>> I tried to totally skip ndo_poll_controller() here. It did avoid hitting
>>> the issue. However, netpoll will drop (fail to send) more packets.
>>>
>>
>> Why is it failing ?
>>
>> If you are under high memory pressure, then maybe if you absolutely want
>> memory to send
>> netpoll packets, you want to grab all NAPI contexts as a way to prevent
>> other cpus
>> from feeding incoming packets to the host and add more memory pressure ;)
>>
>
> I did the test with Eric's latest patch (and disable ndo_poll_controller
> in driver). The result didn't show significant increase in drop packets.
> I guess packet drops in my earlier test was caused by some other changes
> I mixed there.
>
> So I think this patch does fix the issue. Thanks Eric!
Great, this is awesome.
I will prepare a patch series for net tree.
The core infrastructure is just better at being able to drain TX completions
without risking stealing the NAPI context forever.
>
> For ixgbe, I think we need to check napi_complete_done() return value
> anyway. Otherwise, the driver will enable IRQ in polling mode.
>
Sure, let's prepare such optimizations for net-next.
