Re: Question about test_xsk.sh

["Alexis Lothoré" <alexis.lothore@bootlin.com>]

Hello Stanislas, Magnus,

On 1/3/25 10:36, Magnus Karlsson wrote:
> On Thu, 2 Jan 2025 at 23:31, Stanislav Fomichev <stfomichev@gmail.com> wrote:
>>
>> On 12/20, Alexis Lothoré wrote:
>>> Hello all,
>>>
>>> I was looking  at other test candidates for conversion to bpf test_progs
>>> framework (to increase automatic testing scope) and found test_xsk.sh, which
>>> does not seem to have coverage yet in test_progs. This test validates the AF_XDP
>>> socket behavior with different XDP modes (SKB, DRV, zero copy) and socket
>>> configuration (normal, busy polling).
>>>
>>> The testing program looks pretty big, considering all files involved
>>> (test_xsk.sh, xskxceiver.c, xsk.c, the different XDP programs) and the matrix of
>>> tests it runs. So before really diving into it, I would like to ask:
>>> - is it indeed a good/relevant target for integration in test_progs (all tests
>>> look like functional tests, so I guess it is) ?
>>> - if so, is there anyone already working on this ?
>>> - multiple commits on xskxceiver.c hint that the program is also used for
>>> testing on real hardware, could someone confirm that it is still the case
>>> (similar need has been seen with test_xdp_features.sh for example) ? If so, it
>>> means that the current form must be preserved, and it would be an additional
>>> integration into test_progs rather a conversion (then most of the code should be
>>> shared between the non-test_progs and the test_progs version)
>>
>> Since no one came back to you, here is my attempt to answer.. It is a
>> good target but it is indeed a good idea to preserve the ability to
>> run it outside of test_progs framework. Maybe we can eventually run
>> it with the real hw (in loopback mode) from
>> tools/testing/selftests/rivers/net/hw. And I don't think anybody
>> is working on integrating it into test_progs. But Magnus/Maciej should
>> have more context...
> 
> Sorry Alexis for the late reply. I have enjoyed a long vacation over
> the holidays.

No worry, I did not expect quick answers with christmas holidays coming, thanks
to both of you for your answers.

> I agree with Stanislav's reply. The only thing I can add is that we
> really want to preserve the ability to run on real HW as the majority
> of bugs we find are indeed in the zero-copy driver implementations. So
> these real HW/driver tests are more useful to us than the self
> contained tests using veth.

ACK. Based on your answers, and since test_xsk.sh seems to also cover many core
features regarding AF_XDP sockets, I'll work on integrating this in test_progs.
I'll see if the code can be shared between a "on hw" test and a "test progs"
test, and if not possible (eg undesirable code dependency between different kind
of selftests ?), at least replicate the basic AF_XDP tests in test_progs.

Thanks,

Alexis

-- 
Alexis Lothoré, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com