From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: "Pujari, Bimmy" <bimmy.pujari@intel.com>
Cc: bpf <bpf@vger.kernel.org>, Networking <netdev@vger.kernel.org>,
mchehab@kernel.org, "Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Martin Lau" <kafai@fb.com>,
"Maciej Żenczykowski" <maze@google.com>,
"Nikravesh, Ashkan" <ashkan.nikravesh@intel.com>
Subject: Re: [PATCH bpf-next v3 2/2] selftests/bpf: Verifying real time helper function
Date: Thu, 24 Sep 2020 13:22:02 -0700 [thread overview]
Message-ID: <CAEf4BzZ7Srd2k5a_t6JKW9_=cUQVqvxXhd+4rvbpMHKRJAQbiw@mail.gmail.com> (raw)
In-Reply-To: <20200924022557.16561-2-bimmy.pujari@intel.com>
On Wed, Sep 23, 2020 at 7:26 PM <bimmy.pujari@intel.com> wrote:
>
> From: Bimmy Pujari <bimmy.pujari@intel.com>
>
> 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 <bimmy.pujari@intel.com>
> ---
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
>
[...]
next prev parent reply other threads:[~2020-09-24 20:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 2:25 [PATCH bpf-next v3 1/2] bpf: Add bpf_ktime_get_real_ns bimmy.pujari
2020-09-24 2:25 ` [PATCH bpf-next v3 2/2] selftests/bpf: Verifying real time helper function bimmy.pujari
2020-09-24 15:34 ` Daniel Borkmann
2020-09-24 20:22 ` Andrii Nakryiko [this message]
2020-09-25 0:22 ` Pujari, Bimmy
2020-09-24 2:41 ` [PATCH bpf-next v3 1/2] bpf: Add bpf_ktime_get_real_ns Maciej Żenczykowski
2020-09-24 15:31 ` Daniel Borkmann
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