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Date:   Fri, 28 Sep 2018 12:40:17 +0200
From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
To:     Roman Gushchin <guro@fb.com>
Cc:     netdev@vger.kernel.org, Song Liu <songliubraving@fb.com>,
        linux-kernel@vger.kernel.org, kernel-team@fb.com,
        Daniel Borkmann <daniel@iogearbox.net>,
        Alexei Starovoitov <ast@kernel.org>
Subject: Re: [PATCH v3 bpf-next 10/10] selftests/bpf: cgroup local
 storage-based network counters
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On Fri, Sep 28, 2018 at 11:37:26AM +0100, Roman Gushchin wrote:
> > > > > +
> > > > > +	/* Let's check that bytes counter value is reasonable */
> > > > > +	if (netcnt.bytes < packets * 500 || netcnt.bytes > packets * 1500) {
> > > > 
> > > > since packet count is accurate why byte count would vary ?
> > > 
> > > Tbh I'm not sure if the size of the packet here can vary depending
> > > on the environment. Is there a nice way to get the expected size?
> > 
> > ping packets should be fixed size depending on v4 vs v6.
> > If 'ping -6' is used, it will force ipv6.
> > 
> 
> Are we ok to screw up kselftests on v4-only machines?

we already did. Some of the selftests/bpf use ping -6 already.