netdev - Re: [PATCHv3 net-next 4/4] selftests: bonding: use slowwait instead of hard code sleep

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Date: Sun, 4 Feb 2024 16:31:31 +0800
From: Hangbin Liu <liuhangbin@...il.com>
To: Jakub Kicinski <kuba@...nel.org>, Jay Vosburgh <j.vosburgh@...il.com>
Cc: netdev@...r.kernel.org, "David S . Miller" <davem@...emloft.net>,
	Paolo Abeni <pabeni@...hat.com>, Eric Dumazet <edumazet@...gle.com>,
	Liang Li <liali@...hat.com>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>
Subject: Re: [PATCHv3 net-next 4/4] selftests: bonding: use slowwait instead
 of hard code sleep

On Sat, Feb 03, 2024 at 09:41:51AM -0800, Jakub Kicinski wrote:
> On Fri,  2 Feb 2024 10:37:54 +0800 Hangbin Liu wrote:
> > diff --git a/tools/testing/selftests/drivers/net/bonding/bond_macvlan.sh b/tools/testing/selftests/drivers/net/bonding/bond_macvlan.sh
> > index b609fb6231f4..acd3ebed3e20 100755
> > --- a/tools/testing/selftests/drivers/net/bonding/bond_macvlan.sh
> > +++ b/tools/testing/selftests/drivers/net/bonding/bond_macvlan.sh
> > @@ -58,7 +58,7 @@ macvlan_over_bond()
> >  	ip -n ${m2_ns} addr add ${m2_ip4}/24 dev macv0
> >  	ip -n ${m2_ns} addr add ${m2_ip6}/24 dev macv0
> >  
> > -	sleep 2
> > +	slowwait 2 ip netns exec ${c_ns} ping ${s_ip4} -c 1 -W 0.1 &> /dev/null
> >  
> >  	check_connection "${c_ns}" "${s_ip4}" "IPv4: client->server"
> >  	check_connection "${c_ns}" "${s_ip6}" "IPv6: client->server"
> > @@ -69,8 +69,7 @@ macvlan_over_bond()
> >  	check_connection "${m1_ns}" "${m2_ip4}" "IPv4: macvlan_1->macvlan_2"
> >  	check_connection "${m1_ns}" "${m2_ip6}" "IPv6: macvlan_1->macvlan_2"
> >  
> > -
> > -	sleep 5
> > +	slowwait 5 ip netns exec ${s_ns} ping ${c_ip4} -c 1 -W 0.1 &> /dev/null
> >  
> >  	check_connection "${s_ns}" "${c_ip4}" "IPv4: server->client"
> >  	check_connection "${s_ns}" "${c_ip6}" "IPv6: server->client"
> 
> This makes the bond_macvlan.sh test flaky:
> 
> https://netdev.bots.linux.dev/contest.html?test=bond-macvlan-sh

Hi Jakub,

Thanks for the report.

> 
> I repro'd it and the ping in check_connection() fails - neigh resolution
> fails. I guess we need to insert more of the slowwaits?
> 
> Reverting this patch from the pending patch tree fixes it. The runner
> has no KVM support, and runs a VM with 64 CPUs. If I lower the number
> of CPUs to 4 the test passes. I added the note that some flakiness may
> be caused by high CPU count:
> 
> https://github.com/linux-netdev/nipa/wiki/How-to-run-netdev-selftests-CI-style#tips

Sadly, I can't reproduce it with an Intel(R) Xeon(R) CPU E5-2650 v3 @ 2.30GHz,
which has 20 Cores and 40 Processors. From your logs[1][2][3], all the tests
failed when ping from client to macvlan_2. e.g.

# TEST: balance-tlb: IPv4: client->macvlan_1                          [ OK ]
# TEST: balance-tlb: IPv6: client->macvlan_1                          [ OK ]
# TEST: balance-tlb: IPv4: client->macvlan_2                          [FAIL]
# ping failed
# TEST: balance-tlb: IPv6: client->macvlan_2                          [ OK ]

Or

# TEST: balance-alb: IPv4: client->macvlan_1                          [ OK ]
# TEST: balance-alb: IPv6: client->macvlan_1                          [ OK ]
# TEST: balance-alb: IPv4: client->macvlan_2                          [FAIL]
# ping failed
# TEST: balance-alb: IPv6: client->macvlan_2                          [ OK ]

Let us checking the client to macvlan2 connection via slowwait and see
if it works.

[1] https://netdev-2.bots.linux.dev/vmksft-bonding/results/449541/2-bond-macvlan-sh/stdout
[2] https://netdev-2.bots.linux.dev/vmksft-bonding/results/449361/4-bond-macvlan-sh/stdout
[3] https://netdev-2.bots.linux.dev/vmksft-bonding/results/449001/4-bond-macvlan-sh/stdout

Thanks
Hangbin