Re: [PATCH net] ixgbe: check return value of napi_complete_done()

On Sep 20, 2018, at 4:49 PM, Eric Dumazet [off-list ref] wrote:



On 09/20/2018 04:43 PM, Song Liu wrote:

quoted

quoted

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!

For ixgbe, I think we need to check napi_complete_done() return value
anyway. Otherwise, the driver will enable IRQ in polling mode.  

Song