On 05.12.2018 17:25, Slava Shwartsman wrote: > Author: slavash > Date: Wed Dec 5 14:25:03 2018 > New Revision: 341586 > URL: https://svnweb.freebsd.org/changeset/base/341586 > > Log: > mlx5en: Implement backpressure indication. > > The backpressure indication is implemented using an unlimited rate type of > mbuf send tag. When the upper layers typically the socket layer has > obtained such > a tag, it can then query the destination driver queue for the current > amount of space available in the send queue. > > A single mbuf send tag may be referenced multiple times and a refcount has > been added > to the mlx5e_priv structure to track its usage. Because the send tag resides > in the mlx5e_channel structure, there is no need to wait for refcounts to > reach > zero until the mlx4en(4) driver is detached. The channels structure is > persistant > during the lifetime of the mlx5en(4) driver it belongs to and can so be > accessed > without any need of synchronization. > > The mlx5e_snd_tag structure was extended to contain a type field, because > there are now > two different tag types which end up in the driver which need to be > distinguished. > > Submitted by: hselasky@ > Approved by: hselasky (mentor) > MFC after: 1 week > Sponsored by: Mellanox Technologies > @@ -587,27 +609,33 @@ mlx5e_xmit(struct ifnet *ifp, struct mbuf *mb) > struct mlx5e_sq *sq; > int ret; > > - sq = mlx5e_select_queue(ifp, mb); > - if (unlikely(sq == NULL)) { > -#ifdef RATELIMIT > - /* Check for route change */ > - if (mb->m_pkthdr.snd_tag != NULL && > - mb->m_pkthdr.snd_tag->ifp != ifp) { > + if (mb->m_pkthdr.snd_tag != NULL) { > + sq = mlx5e_select_queue_by_send_tag(ifp, mb); > + if (unlikely(sq == NULL)) { > + /* Check for route change */ > + if (mb->m_pkthdr.snd_tag->ifp != ifp) { > + /* Free mbuf */ > + m_freem(mb); > + > + /* > + * Tell upper layers about route > + * change and to re-transmit this > + * packet: > + */ > + return (EAGAIN); > + }
Hi,
I just discovered something strange and found that this commit is the
cause.
The test system has mlx5en 100G interface. It has two vlans: vlan500 and
vlan100.
Via vlan500 it receives some packets flows. Then it routes these packets
into vlan100.
But packets are dropped in mlx5e_xmit() with EAGAIN error code.
# dtrace -n 'fbt::ip6_output:return {printf("%d", arg1);}'
dtrace: description 'fbt::ip6_output:return ' matched 1 probe
CPU ID FUNCTION:NAME
23 54338 ip6_output:return 35
16 54338 ip6_output:return 35
21 54338 ip6_output:return 35
22 54338 ip6_output:return 35
24 54338 ip6_output:return 35
23 54338 ip6_output:return 35
14 54338 ip6_output:return 35
^C
# dtrace -n 'fbt::mlx5e_xmit:return {printf("%d", arg1);}'
dtrace: description 'fbt::mlx5e_xmit:return ' matched 1 probe
CPU ID FUNCTION:NAME
16 69030 mlx5e_xmit:return 35
23 69030 mlx5e_xmit:return 35
26 69030 mlx5e_xmit:return 35
25 69030 mlx5e_xmit:return 35
24 69030 mlx5e_xmit:return 35
21 69030 mlx5e_xmit:return 35
26 69030 mlx5e_xmit:return 35
^C
The kernel config is GENERIC.
13.0-CURRENT #9 r345758+82f3d57(svn_head)-dirty
--
WBR, Andrey V. Elsukov
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