Reduce BH-disable period further by moving cpu_map_build_skb()
outside/before invoking the network stack. And build up a
skb_list that is used for netif_receive_skb_list. This is also
an I-cache optimization.
When injecting packets into the network stack, cpumap uses a special
function named netif_receive_skb_core(), and we create a equivalent list
version named netif_receive_skb_list_core().
Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
---
include/linux/netdevice.h | 1 +
kernel/bpf/cpumap.c | 17 ++++++++++-------
net/core/dev.c | 18 ++++++++++++++++++
3 files changed, 29 insertions(+), 7 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 166fdc0a78b4..37e78dc9f30a 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3621,6 +3621,7 @@ int netif_rx_ni(struct sk_buff *skb);
int netif_receive_skb(struct sk_buff *skb);
int netif_receive_skb_core(struct sk_buff *skb);
void netif_receive_skb_list(struct list_head *head);
+void netif_receive_skb_list_core(struct list_head *head);
gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb);
void napi_gro_flush(struct napi_struct *napi, bool flush_old);
struct sk_buff *napi_get_frags(struct napi_struct *napi);
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index 430103e182a0..cb93df200cd0 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -256,6 +256,7 @@ static int cpu_map_kthread_run(void *data)
while (!kthread_should_stop() || !__ptr_ring_empty(rcpu->queue)) {
unsigned int drops = 0, sched = 0;
void *frames[CPUMAP_BATCH];
+ struct list_head skb_list;
int i, n;
/* Release CPU reschedule checks */
@@ -279,23 +280,25 @@ static int cpu_map_kthread_run(void *data)
*/
n = ptr_ring_consume_batched(rcpu->queue, frames, CPUMAP_BATCH);
- local_bh_disable();
+ INIT_LIST_HEAD(&skb_list);
+
for (i = 0; i < n; i++) {
struct xdp_frame *xdpf = frames[i];
struct sk_buff *skb;
- int ret;
skb = cpu_map_build_skb(rcpu, xdpf);
if (!skb) {
xdp_return_frame(xdpf);
continue;
}
-
- /* Inject into network stack */
- ret = netif_receive_skb_core(skb);
- if (ret == NET_RX_DROP)
- drops++;
+ list_add_tail(&skb->list, &skb_list);
}
+
+ local_bh_disable();
+
+ /* Inject into network stack */
+ netif_receive_skb_list_core(&skb_list);
+
/* Feedback loop via tracepoint */
trace_xdp_cpumap_kthread(rcpu->map_id, n, drops, sched);
diff --git a/net/core/dev.c b/net/core/dev.c
index 9ca2d3abfd1a..1dee7bd895a0 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5297,6 +5297,24 @@ void netif_receive_skb_list(struct list_head *head)
}
EXPORT_SYMBOL(netif_receive_skb_list);
+/**
+ * netif_receive_skb_list_core - special version of netif_receive_skb_list
+ * @head: list of skbs to process.
+ *
+ * More direct receive version of netif_receive_skb_list(). It should
+ * only be used by callers that have a need to skip RPS and Generic XDP.
+ *
+ * This function may only be called from softirq context and interrupts
+ * should be enabled.
+ */
+void netif_receive_skb_list_core(struct list_head *head)
+{
+ rcu_read_lock();
+ __netif_receive_skb_list(head);
+ rcu_read_unlock();
+}
+EXPORT_SYMBOL(netif_receive_skb_list_core);
+
DEFINE_PER_CPU(struct work_struct, flush_works);
/* Network device is going away, flush any packets still pending */
