I agree with you. I will write a separate new test. In the meanwhile I think it 
should be okay to prepare and send just one patch.

Thanks
Bimmy

-----Original Message-----
From: Andrii Nakryiko <[email protected]> 
Sent: Thursday, September 24, 2020 1:22 PM
To: Pujari, Bimmy <[email protected]>
Cc: bpf <[email protected]>; Networking <[email protected]>; 
[email protected]; Alexei Starovoitov <[email protected]>; Daniel Borkmann 
<[email protected]>; Martin Lau <[email protected]>; Maciej Żenczykowski 
<[email protected]>; Nikravesh, Ashkan <[email protected]>
Subject: Re: [PATCH bpf-next v3 2/2] selftests/bpf: Verifying real time helper 
function

On Wed, Sep 23, 2020 at 7:26 PM <[email protected]> wrote:
>
> From: Bimmy Pujari <[email protected]>
>
> Test xdping measures RTT from xdp using monotonic time helper.
> Extending xdping test to use real time helper function in order to 
> verify this helper function.
>
> Signed-off-by: Bimmy Pujari <[email protected]>
> ---

This is exactly the use of REALTIME clock that I was arguing against, and yet 
you are actually creating an example of how to use it for such case. 
CLOCK_REALTIME should not be used to measuring time elapsed (not within the 
same machine, at least), there are strictly better alternatives.

So if you want to write a test for a new helper (assuming everyone else thinks 
it's a good idea), then do just that - write a separate minimal test that tests 
just your new functionality. Don't couple it with a massive XDP program. And 
also don't create unnecessarily almost
400 lines of code churn.

>  .../testing/selftests/bpf/progs/xdping_kern.c | 183 +----------------  
> .../testing/selftests/bpf/progs/xdping_kern.h | 193 ++++++++++++++++++
>  .../bpf/progs/xdping_realtime_kern.c          |   4 +
>  tools/testing/selftests/bpf/test_xdping.sh    |  44 +++-
>  4 files changed, 235 insertions(+), 189 deletions(-)  create mode 
> 100644 tools/testing/selftests/bpf/progs/xdping_kern.h
>  create mode 100644 
> tools/testing/selftests/bpf/progs/xdping_realtime_kern.c
>

[...]

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