Re: [PATCH v3 bpf-next] cpumap: bulk skb using netif_receive_skb_list

Rely on netif_receive_skb_list routine to send skbs converted from
xdp_frames in cpu_map_kthread_run in order to improve i-cache usage.
The proposed patch has been tested running xdp_redirect_cpu bpf sample
available in the kernel tree that is used to redirect UDP frames from
ixgbe driver to a cpumap entry and then to the networking stack.
UDP frames are generated using pkt_gen. Packets are discarded by the
UDP layer.

$xdp_redirect_cpu  --cpu <cpu> --progname xdp_cpu_map0 --dev <eth>

bpf-next: ~2.35Mpps
bpf-next + cpumap skb-list: ~2.72Mpps

Since netif_receive_skb_list does not return number of discarded packets,
remove drop counter from xdp_cpumap_kthread tracepoint and update related
xdp samples.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
Changes since v2:
- remove drop counter and update related xdp samples
- rebased on top of bpf-next

Changes since v1:
- fixed comment
- rebased on top of bpf-next tree
---
 include/trace/events/xdp.h          | 14 +++++---------
 kernel/bpf/cpumap.c                 | 16 +++++++---------
 samples/bpf/xdp_monitor_kern.c      |  6 ++----
 samples/bpf/xdp_monitor_user.c      | 14 ++++++--------
 samples/bpf/xdp_redirect_cpu_kern.c | 12 +++++-------
 samples/bpf/xdp_redirect_cpu_user.c | 10 ++++------
 6 files changed, 29 insertions(+), 43 deletions(-)

diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h
index fcad3645a70b..52ecfe9c7e25 100644
--- a/include/trace/events/xdp.h
+++ b/include/trace/events/xdp.h

@@ -184,16 +184,15 @@ DEFINE_EVENT(xdp_redirect_template, xdp_redirect_map_err,
 
 TRACE_EVENT(xdp_cpumap_kthread,
 
-	TP_PROTO(int map_id, unsigned int processed,  unsigned int drops,
-		 int sched, struct xdp_cpumap_stats *xdp_stats),
+	TP_PROTO(int map_id, unsigned int processed, int sched,
+		 struct xdp_cpumap_stats *xdp_stats),
 
-	TP_ARGS(map_id, processed, drops, sched, xdp_stats),
+	TP_ARGS(map_id, processed, sched, xdp_stats),
 
 	TP_STRUCT__entry(
 		__field(int, map_id)
 		__field(u32, act)
 		__field(int, cpu)
-		__field(unsigned int, drops)
 		__field(unsigned int, processed)

 		__field(int, sched)
 		__field(unsigned int, xdp_pass)

@@ -205,7 +204,6 @@ TRACE_EVENT(xdp_cpumap_kthread,
 		__entry->map_id		= map_id;
 		__entry->act		= XDP_REDIRECT;
 		__entry->cpu		= smp_processor_id();
-		__entry->drops		= drops;
 		__entry->processed	= processed;
 		__entry->sched	= sched;
 		__entry->xdp_pass	= xdp_stats->pass;

@@ -215,13 +213,11 @@ TRACE_EVENT(xdp_cpumap_kthread,
 
 	TP_printk("kthread"
 		  " cpu=%d map_id=%d action=%s"
-		  " processed=%u drops=%u"
-		  " sched=%d"
+		  " processed=%u sched=%u"
 		  " xdp_pass=%u xdp_drop=%u xdp_redirect=%u",
 		  __entry->cpu, __entry->map_id,
 		  __print_symbolic(__entry->act, __XDP_ACT_SYM_TAB),
-		  __entry->processed, __entry->drops,
-		  __entry->sched,
+		  __entry->processed, __entry->sched,
 		  __entry->xdp_pass, __entry->xdp_drop, __entry->xdp_redirect)
 );