This is a proposal to add QoS support to bgmac driver, allowing to use
(possibly) all of the tx queues supported by the hardware.
The bgmac device is allocated as an ethernet multiqueue network device,
reporting the (maximum) tx queues supported by the hardware to the kernel.
The default queue selection mechenism is replaced with the
bgmac_select_queue function, mapping the priorities of the skbs to a specific
tx queue number.
Later this number is used in the bgmax_start_xmit function to select the right
tx queue, on which the new skb is added.
The hardware will generate an interrupt when the skb is handled, in which it
reports on what hardware queue (number/id) the event occured, allowing to call
bgmac_dma_tx_free on the right tx queue/ring.
Mapping is according to 802.1d priority to traffic class mapping, as found in
et_linux.c :
TX_Q1, /* 0 BE TC_BE Best Effort */
TX_Q0, /* 1 BK TC_BK Background */
TX_Q0, /* 2 -- TC_BK Background */
TX_Q1, /* 3 EE TC_BE Best Effort */
TX_Q2, /* 4 CL TC_CL Controlled Load */
TX_Q2, /* 5 VI TC_CL Controlled Load */
TX_Q3, /* 6 VO TC_VO Voice */
TX_Q3 /* 7 NC TC_VO Voice */
Additionally any other value is mapped on TX_Q0..
Impact on the source code is rather limited, some extra local variables for
netdev_queue, queue_id (u16), and all netif_.*_queue calls converted to
appropriate netdif_tx_.*_queue calls.
I did not test extensively yet, but proof of concept works and is easily
tested by adding some debug code to the driver (in bgmac_dma_tx_add,
bgmac_poll and bgmac_select_queue functions) and using the ping command
on command line and the dropbear ssh (which uses a non-default TOS value
on packets: Minimize Delay). Console output shows the following:
root@OpenWrt:/# ping 192.168.1.113
PING 192.168.1.113 (192.168.1.113): 56 data bytes
[ 58.304000] bgmac bcma0:1: bgmac_select_queue based on priority 0x0
[ 58.316000] bgmac bcma0:1: Select tx queue 1 for packet
[ 58.320000] bgmac bcma0:1: Received interrupt for tx queue 1
[ 58.328000] bgmac bcma0:1: bgmac_select_queue based on priority 0x0
[ 58.332000] bgmac bcma0:1: Select tx queue 1 for packet
[ 58.340000] bgmac bcma0:1: Received interrupt for tx queue 1
64 bytes from 192.168.1.113: seq=0 ttl=64 time=40.513 ms
[ 59.344000] bgmac bcma0:1: bgmac_select_queue based on priority 0x0
[ 59.352000] bgmac bcma0:1: Select tx queue 1 for packet
[ 59.356000] bgmac bcma0:1: Received interrupt for tx queue 1
64 bytes from 192.168.1.113: seq=1 ttl=64 time=18.595 ms
[ 60.364000] bgmac bcma0:1: bgmac_select_queue based on priority 0x0
[ 60.372000] bgmac bcma0:1: Select tx queue 1 for packet
[ 60.376000] bgmac bcma0:1: Received interrupt for tx queue 1
64 bytes from 192.168.1.113: seq=2 ttl=64 time=18.550 ms
^C
--- 192.168.1.113 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
root@OpenWrt:/# ssh [email protected]
[ 105.992000] bgmac bcma0:1: bgmac_select_queue based on priority 0x0
[ 106.000000] bgmac bcma0:1: Select tx queue 1 for packet
[ 106.004000] bgmac bcma0:1: Received interrupt for tx queue 1
[ 106.012000] bgmac bcma0:1: bgmac_select_queue based on priority 0x0
[ 106.016000] bgmac bcma0:1: Select tx queue 1 for packet
[ 106.024000] bgmac bcma0:1: Received interrupt for tx queue 1
[ 106.032000] bgmac bcma0:1: bgmac_select_queue based on priority 0x6
[ 106.036000] bgmac bcma0:1: Select tx queue 3 for packet
[ 106.044000] bgmac bcma0:1: Received interrupt for tx queue 3
[ 106.048000] bgmac bcma0:1: bgmac_select_queue based on priority 0x6
[ 106.056000] bgmac bcma0:1: Select tx queue 3 for packet
[ 106.060000] bgmac bcma0:1: Received interrupt for tx queue 3
[ 106.072000] bgmac bcma0:1: bgmac_select_queue based on priority 0x6
...
Host '192.168.1.113' is not in the trusted hosts file.
(fingerprint md5 b7:12:75:ca:65:cb:c7:60:59:35:6a:5d:28:6d:27:83)
Do you want to continue connecting? (y/n)
[ 106.400000] bgmac bcma0:1: bgmac_select_queue based on priority 0x6
[ 106.404000] bgmac bcma0:1: Select tx queue 3 for packet
[ 106.408000] bgmac bcma0:1: Received interrupt for tx queue 3
y
[ 111.776000] bgmac bcma0:1: bgmac_select_queue based on priority 0x6
...
This patch is generated from git trunk.. Any comments/suggestions/ideas very
welcome...
Signed-off-by: Tijs Van Buggenhout <[email protected]>
---
diff --git a/drivers/net/ethernet/broadcom/bgmac.c
b/drivers/net/ethernet/broadcom/bgmac.c
index 3fd3288..58b1d09 100644
--- a/drivers/net/ethernet/broadcom/bgmac.c
+++ b/drivers/net/ethernet/broadcom/bgmac.c
@@ -15,6 +15,8 @@
#include <linux/mii.h>
#include <linux/interrupt.h>
#include <linux/dma-mapping.h>
+#include <linux/pkt_sched.h> /* TC defines */
+#include <linux/skbuff.h> /* skb_get_queue_mapping */
#include <asm/mach-bcm47xx/nvram.h>
static const struct bcma_device_id bgmac_bcma_tbl[] = {
@@ -102,15 +104,22 @@ static void bgmac_dma_tx_enable(struct bgmac *bgmac,
static netdev_tx_t bgmac_dma_tx_add(struct bgmac *bgmac,
struct bgmac_dma_ring *ring,
- struct sk_buff *skb)
+ struct sk_buff *skb,
+ u16 queue_id)
{
struct device *dma_dev = bgmac->core->dma_dev;
struct net_device *net_dev = bgmac->net_dev;
+ struct netdev_queue *tx_queue;
struct bgmac_dma_desc *dma_desc;
struct bgmac_slot_info *slot;
u32 ctl0, ctl1;
int free_slots;
+ if ((tx_queue = netdev_get_tx_queue(net_dev, queue_id)) == NULL) {
+ bgmac_err(bgmac, "Error mapping skb to TX queue (id %u)\n",
queue_id);
+ goto err_drop;
+ }
+
if (skb->len > BGMAC_DESC_CTL1_LEN) {
bgmac_err(bgmac, "Too long skb (%d)\n", skb->len);
goto err_stop_drop;
@@ -122,7 +131,7 @@ static netdev_tx_t bgmac_dma_tx_add(struct bgmac *bgmac,
free_slots = ring->start - ring->end;
if (free_slots == 1) {
bgmac_err(bgmac, "TX ring is full, queue should be stopped!\n");
- netif_stop_queue(net_dev);
+ netif_tx_stop_queue(tx_queue);
return NETDEV_TX_BUSY;
}
@@ -160,20 +169,22 @@ static netdev_tx_t bgmac_dma_tx_add(struct bgmac *bgmac,
/* Always keep one slot free to allow detecting bugged calls. */
if (--free_slots == 1)
- netif_stop_queue(net_dev);
+ netif_tx_stop_queue(tx_queue);
return NETDEV_TX_OK;
err_stop_drop:
- netif_stop_queue(net_dev);
+ netif_tx_stop_queue(tx_queue);
+err_drop:
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
/* Free transmitted packets */
-static void bgmac_dma_tx_free(struct bgmac *bgmac, struct bgmac_dma_ring *ring)
+static void bgmac_dma_tx_free(struct bgmac *bgmac, struct bgmac_dma_ring
*ring, u16 queue_id)
{
struct device *dma_dev = bgmac->core->dma_dev;
+ struct netdev_queue *tx_queue = netdev_get_tx_queue(bgmac->net_dev,
queue_id);
int empty_slot;
bool freed = false;
@@ -204,8 +215,8 @@ static void bgmac_dma_tx_free(struct bgmac *bgmac, struct
bgmac_dma_ring *ring)
freed = true;
}
- if (freed && netif_queue_stopped(bgmac->net_dev))
- netif_wake_queue(bgmac->net_dev);
+ if (freed && netif_tx_queue_stopped(tx_queue))
+ netif_tx_wake_queue(tx_queue);
}
static void bgmac_dma_rx_reset(struct bgmac *bgmac, struct bgmac_dma_ring
*ring)
@@ -1096,14 +1107,23 @@ static irqreturn_t bgmac_interrupt(int irq, void
*dev_id)
static int bgmac_poll(struct napi_struct *napi, int weight)
{
+ static const u32 tx_ring[BGMAC_MAX_TX_RINGS] = {
+ BGMAC_IS_TX0, BGMAC_IS_TX1,
+ BGMAC_IS_TX2, BGMAC_IS_TX3,
+ };
struct bgmac *bgmac = container_of(napi, struct bgmac, napi);
struct bgmac_dma_ring *ring;
- int handled = 0;
-
- if (bgmac->int_status & BGMAC_IS_TX0) {
- ring = &bgmac->tx_ring[0];
- bgmac_dma_tx_free(bgmac, ring);
- bgmac->int_status &= ~BGMAC_IS_TX0;
+ int handled = 0, i;
+
+ if (bgmac->int_status & BGMAC_IS_TX_MASK) {
+ for (i = 0 ; (bgmac->int_status & BGMAC_IS_TX_MASK) &&
+ i < BGMAC_MAX_TX_RINGS ; i++) {
+ if (bgmac->int_status & tx_ring[i]) {
+ ring = &bgmac->tx_ring[i];
+ bgmac_dma_tx_free(bgmac, ring, (u16)i);
+ bgmac->int_status &= ~tx_ring[i];
+ }
+ }
}
if (bgmac->int_status & BGMAC_IS_RX) {
@@ -1172,10 +1192,11 @@ static netdev_tx_t bgmac_start_xmit(struct sk_buff *skb,
{
struct bgmac *bgmac = netdev_priv(net_dev);
struct bgmac_dma_ring *ring;
+ u16 queue_id = 0;
- /* No QOS support yet */
- ring = &bgmac->tx_ring[0];
- return bgmac_dma_tx_add(bgmac, ring, skb);
+ queue_id = skb_get_queue_mapping(skb);
+ ring = &bgmac->tx_ring[queue_id];
+ return bgmac_dma_tx_add(bgmac, ring, skb, queue_id);
}
static int bgmac_set_mac_address(struct net_device *net_dev, void *addr)
@@ -1217,6 +1238,32 @@ static int bgmac_ioctl(struct net_device *net_dev,
struct ifreq *ifr, int cmd)
}
}
+static u16 bgmac_select_queue(struct net_device *net_dev, struct sk_buff *skb)
+{
+ u32 priority = skb->priority;
+
+ /* 802.1d priority to traffic class mapping for 4 queues */
+ switch (priority) {
+ case TC_PRIO_BESTEFFORT: /* Best effort */
+ case 3: /* Excellent effort */
+ /* Best effort queue TX_Q1 */
+ return 1;
+ case TC_PRIO_INTERACTIVE_BULK: /* Controlled load */
+ case 5: /* Video */
+ /* Controlled Load queue TX_Q2 */
+ return 2;
+ case TC_PRIO_INTERACTIVE: /* Voice */
+ case TC_PRIO_CONTROL: /* Network control */
+ /* Interactive queue TX_Q3 */
+ return 3;
+ case TC_PRIO_FILLER:
+ case TC_PRIO_BULK:
+ default:
+ /* Background queue TX_Q0 */
+ return 0;
+ }
+}
+
static const struct net_device_ops bgmac_netdev_ops = {
.ndo_open = bgmac_open,
.ndo_stop = bgmac_stop,
@@ -1225,6 +1272,7 @@ static const struct net_device_ops bgmac_netdev_ops = {
.ndo_set_mac_address = bgmac_set_mac_address,
.ndo_validate_addr = eth_validate_addr,
.ndo_do_ioctl = bgmac_ioctl,
+ .ndo_select_queue = bgmac_select_queue,
};
/**************************************************
@@ -1330,7 +1378,7 @@ static int bgmac_probe(struct bcma_device *core)
}
/* Allocation and references */
- net_dev = alloc_etherdev(sizeof(*bgmac));
+ net_dev = alloc_etherdev_mq(sizeof(*bgmac), BGMAC_MAX_TX_RINGS);
if (!net_dev)
return -ENOMEM;
net_dev->netdev_ops = &bgmac_netdev_ops;
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