Re: [PATCH v9 1/4] liburing: add api to set napi busy poll settings

[Jens Axboe <axboe@kernel.dk>]

On 2/2/24 3:46 PM, Jens Axboe wrote:
> On 2/2/24 3:20 PM, Jens Axboe wrote:
>> On 2/2/24 1:23 PM, Olivier Langlois wrote:
>>> On Fri, 2024-02-02 at 13:14 -0700, Jens Axboe wrote:
>>>>
>>>> Ah gotcha, yeah that?s odd and could not ever have worked. I wonder
>>>> how that was tested?
>>>>
>>>> I?ll setup a liburing branch as well.
>>>>
>>> It is easy. You omit to check the function return value by telling to
>>> yourself that it cannot fail...
>>>
>>> I caught my mistake on a second pass code review...
>>
>> Oh I can see how that can happen, but then there should be no functional
>> changes in terms of latency... Which means that it was never tested. The
>> test results were from the original postings, so probably just fine.
>> It's just that later versions would've failed. Looking at the example
>> test case, it doesn't check the return value.
> 
> Setup a 'napi' branch with the patches, and some fixes on top. It's a
> start... I'll try the example ping test here, just need to get off a
> plane and be able to access test boxes.

Added ipv4 support to the napi example code, and here's what I get.
Stock settings, no NAPI, 100k packets:

 rtt(us) min/avg/max/mdev = 31.730/37.006/87.960/0.497

and with -t10 -b enabled:

 rtt(us) min/avg/max/mdev = 23.250/29.795/63.511/1.203

So it seems to work fine as-is, with the current branch. I've added some
tweaks on the liburing napi branch, but mostly just little fixes.

-- 
Jens Axboe