Re: [PATCH 04/15] net: Use trace_invoke_##name() at guarded tracepoint call sites

Vineeth Remanan Pillai
2026-03-18T14:13:34Z

On Wed, Mar 18, 2026 at 9:40 AM Vineeth Remanan Pillai
<vineeth@bitbyteword.org> wrote:
>
> On Thu, Mar 12, 2026 at 11:31 AM Aaron Conole <aconole@redhat.com> wrote:
> >
> > "Vineeth Pillai (Google)" <vineeth@bitbyteword.org> writes:
> >
> > > Replace trace_foo() with the new trace_invoke_foo() at sites already
> > > guarded by trace_foo_enabled(), avoiding a redundant
> > > static_branch_unlikely() re-evaluation inside the tracepoint.
> > > trace_invoke_foo() calls the tracepoint callbacks directly without
> > > utilizing the static branch again.
> > >
> > > Suggested-by: Steven Rostedt <rostedt@goodmis.org>
> > > Suggested-by: Peter Zijlstra <peterz@infradead.org>
> > > Signed-off-by: Vineeth Pillai (Google) <vineeth@bitbyteword.org>
> > > Assisted-by: Claude:claude-sonnet-4-6
> > > ---
> > > net/core/dev.c | 2 +-
> > > net/core/xdp.c | 2 +-
> > > net/openvswitch/actions.c | 2 +-
> > > net/openvswitch/datapath.c | 2 +-
> > > net/sctp/outqueue.c | 2 +-
> > > net/tipc/node.c | 2 +-
> > > 6 files changed, 6 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/net/core/dev.c b/net/core/dev.c
> > > index 14a83f2035b93..a48fae2bbf57e 100644
> > > --- a/net/core/dev.c
> > > +++ b/net/core/dev.c
> > > @@ -6444,7 +6444,7 @@ void netif_receive_skb_list(struct list_head *head)
> > > return;
> > > if (trace_netif_receive_skb_list_entry_enabled()) {
> > > list_for_each_entry(skb, head, list)
> > > - trace_netif_receive_skb_list_entry(skb);
> > > + trace_invoke_netif_receive_skb_list_entry(skb);
> > > }
> > > netif_receive_skb_list_internal(head);
> > > trace_netif_receive_skb_list_exit(0);
> > > diff --git a/net/core/xdp.c b/net/core/xdp.c
> > > index 9890a30584ba7..53acc887c3434 100644
> > > --- a/net/core/xdp.c
> > > +++ b/net/core/xdp.c
> > > @@ -362,7 +362,7 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
> > > xsk_pool_set_rxq_info(allocator, xdp_rxq);
> > >
> > > if (trace_mem_connect_enabled() && xdp_alloc)
> > > - trace_mem_connect(xdp_alloc, xdp_rxq);
> > > + trace_invoke_mem_connect(xdp_alloc, xdp_rxq);
> > > return 0;
> > > }
> > >
> > > diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
> > > index 792ca44a461da..420eb19322e85 100644
> > > --- a/net/openvswitch/actions.c
> > > +++ b/net/openvswitch/actions.c
> > > @@ -1259,7 +1259,7 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
> > > int err = 0;
> > >
> > > if (trace_ovs_do_execute_action_enabled())
> > > - trace_ovs_do_execute_action(dp, skb, key, a, rem);
> > > + trace_invoke_ovs_do_execute_action(dp, skb, key, a, rem);
> >
> > Maybe we should just remove the guard here instead of calling the
> > invoke. That seems better to me. It wouldn't need to belong to this
> > series.
> >
> > > /* Actions that rightfully have to consume the skb should do it
> > > * and return directly.
> > > diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
> > > index e209099218b41..02451629e888e 100644
> > > --- a/net/openvswitch/datapath.c
> > > +++ b/net/openvswitch/datapath.c
> > > @@ -335,7 +335,7 @@ int ovs_dp_upcall(struct datapath *dp, struct sk_buff *skb,
> > > int err;
> > >
> > > if (trace_ovs_dp_upcall_enabled())
> > > - trace_ovs_dp_upcall(dp, skb, key, upcall_info);
> > > + trace_invoke_ovs_dp_upcall(dp, skb, key, upcall_info);
> >
> > Same as above. Seems OVS tracepoints are the only ones that include
> > the guard without any real reason.
> >
>
> Makes sense. Its simple enough that I think I will include it as a
> separate patch in v2 and remove these changes from this patch. Thanks
> for pointing it out.
>
On a second look, I'm not sure if this was for performance reasons.
The discussion in the io_uring patch in this series points out that
the check made there was deliberate and for performance reasons to
avoid 6 mov instruction in the hot path. Just wanted to double check
if that was the case here, before I remove the check?

Thanks,
Vineeth