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Date: Mon, 21 Jan 2019 17:33:56 +0100
From: bjorn.topel@...il.com
To: intel-wired-lan@...ts.osuosl.org
Cc: Björn Töpel <bjorn.topel@...el.com>,
brouer@...hat.com, magnus.karlsson@...el.com,
magnus.karlsson@...il.com, netdev@...r.kernel.org
Subject: [PATCH] i40e: replace switch-statement with if-clause
From: Björn Töpel <bjorn.topel@...el.com>
GCC will generate jump tables for switch-statements with more than 5
case statements. An entry into the jump table is an indirect call,
which means that for CONFIG_RETPOLINE builds, this is rather
expensive.
This commit replaces the switch-statement that acts on the XDP program
result with an if-clause.
The if-clause was also refactored into a common function that can be
used by AF_XDP zero-copy and non-zero-copy code.
Performance prior this patch:
$ sudo ./xdp_rxq_info --dev enp134s0f0 --action XDP_DROP
Running XDP on dev:enp134s0f0 (ifindex:7) action:XDP_DROP options:no_touch
XDP stats CPU pps issue-pps
XDP-RX CPU 20 18983018 0
XDP-RX CPU total 18983018
RXQ stats RXQ:CPU pps issue-pps
rx_queue_index 20:20 18983012 0
rx_queue_index 20:sum 18983012
$ sudo ./xdpsock -i enp134s0f0 -q 20 -n 2 -z -r
sock0@...134s0f0:20 rxdrop
pps pkts 2.00
rx 14,641,496 144,751,092
tx 0 0
And after:
$ sudo ./xdp_rxq_info --dev enp134s0f0 --action XDP_DROP
Running XDP on dev:enp134s0f0 (ifindex:7) action:XDP_DROP options:no_touch
XDP stats CPU pps issue-pps
XDP-RX CPU 20 24000986 0
XDP-RX CPU total 24000986
RXQ stats RXQ:CPU pps issue-pps
rx_queue_index 20:20 24000985 0
rx_queue_index 20:sum 24000985
+26%
$ sudo ./xdpsock -i enp134s0f0 -q 20 -n 2 -z -r
sock0@...134s0f0:20 rxdrop
pps pkts 2.00
rx 17,623,578 163,503,263
tx 0 0
+20%
Signed-off-by: Björn Töpel <bjorn.topel@...el.com>
---
drivers/net/ethernet/intel/i40e/i40e_txrx.c | 31 ++++---------------
.../ethernet/intel/i40e/i40e_txrx_common.h | 27 ++++++++++++++++
drivers/net/ethernet/intel/i40e/i40e_xsk.c | 24 ++------------
3 files changed, 35 insertions(+), 47 deletions(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index a7e14e98889f..b339b7ee6380 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -2,7 +2,6 @@
/* Copyright(c) 2013 - 2018 Intel Corporation. */
#include <linux/prefetch.h>
-#include <linux/bpf_trace.h>
#include <net/xdp.h>
#include "i40e.h"
#include "i40e_trace.h"
@@ -2195,41 +2194,23 @@ int i40e_xmit_xdp_tx_ring(struct xdp_buff *xdp, struct i40e_ring *xdp_ring)
static struct sk_buff *i40e_run_xdp(struct i40e_ring *rx_ring,
struct xdp_buff *xdp)
{
- int err, result = I40E_XDP_PASS;
- struct i40e_ring *xdp_ring;
struct bpf_prog *xdp_prog;
+ int result;
u32 act;
rcu_read_lock();
xdp_prog = READ_ONCE(rx_ring->xdp_prog);
- if (!xdp_prog)
+ if (!xdp_prog) {
+ result = I40E_XDP_PASS;
goto xdp_out;
+ }
prefetchw(xdp->data_hard_start); /* xdp_frame write */
act = bpf_prog_run_xdp(xdp_prog, xdp);
- switch (act) {
- case XDP_PASS:
- break;
- case XDP_TX:
- xdp_ring = rx_ring->vsi->xdp_rings[rx_ring->queue_index];
- result = i40e_xmit_xdp_tx_ring(xdp, xdp_ring);
- break;
- case XDP_REDIRECT:
- err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog);
- result = !err ? I40E_XDP_REDIR : I40E_XDP_CONSUMED;
- break;
- default:
- bpf_warn_invalid_xdp_action(act);
- /* fall through */
- case XDP_ABORTED:
- trace_xdp_exception(rx_ring->netdev, xdp_prog, act);
- /* fall through -- handle aborts by dropping packet */
- case XDP_DROP:
- result = I40E_XDP_CONSUMED;
- break;
- }
+ i40e_xdp_do_action(act, &result, rx_ring, xdp, xdp_prog);
+
xdp_out:
rcu_read_unlock();
return ERR_PTR(-result);
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx_common.h b/drivers/net/ethernet/intel/i40e/i40e_txrx_common.h
index 8af0e99c6c0d..8cc4d8365f9e 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx_common.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx_common.h
@@ -4,6 +4,8 @@
#ifndef I40E_TXRX_COMMON_
#define I40E_TXRX_COMMON_
+#include <linux/bpf_trace.h>
+
void i40e_fd_handle_status(struct i40e_ring *rx_ring,
union i40e_rx_desc *rx_desc, u8 prog_id);
int i40e_xmit_xdp_tx_ring(struct xdp_buff *xdp, struct i40e_ring *xdp_ring);
@@ -88,4 +90,29 @@ void i40e_xsk_clean_rx_ring(struct i40e_ring *rx_ring);
void i40e_xsk_clean_tx_ring(struct i40e_ring *tx_ring);
bool i40e_xsk_any_rx_ring_enabled(struct i40e_vsi *vsi);
+static inline void i40e_xdp_do_action(u32 act, int *result,
+ struct i40e_ring *rx_ring,
+ struct xdp_buff *xdp,
+ struct bpf_prog *xdp_prog)
+{
+ struct i40e_ring *xdp_ring;
+ int err;
+
+ if (act == XDP_TX) {
+ xdp_ring = rx_ring->vsi->xdp_rings[rx_ring->queue_index];
+ *result = i40e_xmit_xdp_tx_ring(xdp, xdp_ring);
+ } else if (act == XDP_REDIRECT) {
+ err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog);
+ *result = !err ? I40E_XDP_REDIR : I40E_XDP_CONSUMED;
+ } else if (act == XDP_PASS) {
+ *result = I40E_XDP_PASS;
+ } else if (act == XDP_DROP) {
+ *result = I40E_XDP_CONSUMED;
+ } else {
+ if (act != XDP_ABORTED)
+ bpf_warn_invalid_xdp_action(act);
+ trace_xdp_exception(rx_ring->netdev, xdp_prog, act);
+ *result = I40E_XDP_CONSUMED;
+ }
+}
#endif /* I40E_TXRX_COMMON_ */
diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index 870cf654e436..1ed56475ec78 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -282,9 +282,8 @@ int i40e_xsk_umem_setup(struct i40e_vsi *vsi, struct xdp_umem *umem,
**/
static int i40e_run_xdp_zc(struct i40e_ring *rx_ring, struct xdp_buff *xdp)
{
- int err, result = I40E_XDP_PASS;
- struct i40e_ring *xdp_ring;
struct bpf_prog *xdp_prog;
+ int result;
u32 act;
rcu_read_lock();
@@ -294,26 +293,7 @@ static int i40e_run_xdp_zc(struct i40e_ring *rx_ring, struct xdp_buff *xdp)
xdp_prog = READ_ONCE(rx_ring->xdp_prog);
act = bpf_prog_run_xdp(xdp_prog, xdp);
xdp->handle += xdp->data - xdp->data_hard_start;
- switch (act) {
- case XDP_PASS:
- break;
- case XDP_TX:
- xdp_ring = rx_ring->vsi->xdp_rings[rx_ring->queue_index];
- result = i40e_xmit_xdp_tx_ring(xdp, xdp_ring);
- break;
- case XDP_REDIRECT:
- err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog);
- result = !err ? I40E_XDP_REDIR : I40E_XDP_CONSUMED;
- break;
- default:
- bpf_warn_invalid_xdp_action(act);
- case XDP_ABORTED:
- trace_xdp_exception(rx_ring->netdev, xdp_prog, act);
- /* fallthrough -- handle aborts by dropping packet */
- case XDP_DROP:
- result = I40E_XDP_CONSUMED;
- break;
- }
+ i40e_xdp_do_action(act, &result, rx_ring, xdp, xdp_prog);
rcu_read_unlock();
return result;
}
--
2.19.1
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