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Commit b19fa1fa authored by David S. Miller's avatar David S. Miller
Browse files

net: Delete NETDEVICES_MULTIQUEUE kconfig option. 



Multiple TX queue support is a core networking feature.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c773e847

Documentation/networking/multiqueue.txt

+1 −78
Original line number Diff line number Diff line
@@ -3,19 +3,11 @@ 
		===========================================



Section 1: Base driver requirements for implementing multiqueue support

Section 2: Qdisc support for multiqueue devices

Section 3: Brief howto using PRIO or RR for multiqueue devices





Intro: Kernel support for multiqueue devices

---------------------------------------------------------



Kernel support for multiqueue devices is only an API that is presented to the

netdevice layer for base drivers to implement.  This feature is part of the

core networking stack, and all network devices will be running on the

multiqueue-aware stack.  If a base driver only has one queue, then these

changes are transparent to that driver.



Kernel support for multiqueue devices is always present.



Section 1: Base driver requirements for implementing multiqueue support

-----------------------------------------------------------------------
@@ -43,73 +35,4 @@ bitmap on device initialization. Below is an example from e1000: 
		netdev->features |= NETIF_F_MULTI_QUEUE;

#endif





Section 2: Qdisc support for multiqueue devices

-----------------------------------------------



Currently two qdiscs support multiqueue devices.  A new round-robin qdisc,

sch_rr, and sch_prio. The qdisc is responsible for classifying the skb's to

bands and queues, and will store the queue mapping into skb->queue_mapping.

Use this field in the base driver to determine which queue to send the skb

to.



sch_rr has been added for hardware that doesn't want scheduling policies from

software, so it's a straight round-robin qdisc.  It uses the same syntax and

classification priomap that sch_prio uses, so it should be intuitive to

configure for people who've used sch_prio.



In order to utilitize the multiqueue features of the qdiscs, the network

device layer needs to enable multiple queue support.  This can be done by

selecting NETDEVICES_MULTIQUEUE under Drivers.



The PRIO qdisc naturally plugs into a multiqueue device.  If

NETDEVICES_MULTIQUEUE is selected, then on qdisc load, the number of

bands requested is compared to the number of queues on the hardware.  If they

are equal, it sets a one-to-one mapping up between the queues and bands.  If

they're not equal, it will not load the qdisc.  This is the same behavior

for RR.  Once the association is made, any skb that is classified will have

skb->queue_mapping set, which will allow the driver to properly queue skb's

to multiple queues.





Section 3: Brief howto using PRIO and RR for multiqueue devices

---------------------------------------------------------------



The userspace command 'tc,' part of the iproute2 package, is used to configure

qdiscs.  To add the PRIO qdisc to your network device, assuming the device is

called eth0, run the following command:



# tc qdisc add dev eth0 root handle 1: prio bands 4 multiqueue



This will create 4 bands, 0 being highest priority, and associate those bands

to the queues on your NIC.  Assuming eth0 has 4 Tx queues, the band mapping

would look like:



band 0 => queue 0

band 1 => queue 1

band 2 => queue 2

band 3 => queue 3



Traffic will begin flowing through each queue if your TOS values are assigning

traffic across the various bands.  For example, ssh traffic will always try to

go out band 0 based on TOS -> Linux priority conversion (realtime traffic),

so it will be sent out queue 0.  ICMP traffic (pings) fall into the "normal"

traffic classification, which is band 1.  Therefore pings will be send out

queue 1 on the NIC.



Note the use of the multiqueue keyword.  This is only in versions of iproute2

that support multiqueue networking devices; if this is omitted when loading

a qdisc onto a multiqueue device, the qdisc will load and operate the same

if it were loaded onto a single-queue device (i.e. - sends all traffic to

queue 0).



Another alternative to multiqueue band allocation can be done by using the

multiqueue option and specify 0 bands.  If this is the case, the qdisc will

allocate the number of bands to equal the number of queues that the device

reports, and bring the qdisc online.



The behavior of tc filters remains the same, where it will override TOS priority

classification.





Author: Peter P. Waskiewicz Jr. <peter.p.waskiewicz.jr@intel.com>

drivers/net/Kconfig

+0 −8
Original line number Diff line number Diff line
@@ -26,14 +26,6 @@ menuconfig NETDEVICES 
# that for each of the symbols.

if NETDEVICES



config NETDEVICES_MULTIQUEUE

	bool "Netdevice multiple hardware queue support"

	---help---

	  Say Y here if you want to allow the network stack to use multiple

	  hardware TX queues on an ethernet device.



	  Most people will say N here.



config IFB

	tristate "Intermediate Functional Block support"

	depends on NET_CLS_ACT

drivers/net/cpmac.c

+0 −14
Original line number Diff line number Diff line
@@ -569,11 +569,7 @@ static int cpmac_start_xmit(struct sk_buff *skb, struct net_device *dev) 


	len = max(skb->len, ETH_ZLEN);

	queue = skb_get_queue_mapping(skb);

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

	netif_stop_subqueue(dev, queue);

#else

	netif_stop_queue(dev);

#endif



	desc = &priv->desc_ring[queue];

	if (unlikely(desc->dataflags & CPMAC_OWN)) {
@@ -626,24 +622,14 @@ static void cpmac_end_xmit(struct net_device *dev, int queue) 


		dev_kfree_skb_irq(desc->skb);

		desc->skb = NULL;

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

		if (netif_subqueue_stopped(dev, queue))

			netif_wake_subqueue(dev, queue);

#else

		if (netif_queue_stopped(dev))

			netif_wake_queue(dev);

#endif

	} else {

		if (netif_msg_tx_err(priv) && net_ratelimit())

			printk(KERN_WARNING

			       "%s: end_xmit: spurious interrupt\n", dev->name);

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

		if (netif_subqueue_stopped(dev, queue))

			netif_wake_subqueue(dev, queue);

#else

		if (netif_queue_stopped(dev))

			netif_wake_queue(dev);

#endif

	}

}

drivers/net/ixgbe/ixgbe_ethtool.c

+0 −6
Original line number Diff line number Diff line
@@ -252,21 +252,15 @@ static int ixgbe_set_tso(struct net_device *netdev, u32 data) 
		netdev->features |= NETIF_F_TSO;

		netdev->features |= NETIF_F_TSO6;

	} else {

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

		struct ixgbe_adapter *adapter = netdev_priv(netdev);

		int i;

#endif

		netif_stop_queue(netdev);

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

		for (i = 0; i < adapter->num_tx_queues; i++)

			netif_stop_subqueue(netdev, i);

#endif

		netdev->features &= ~NETIF_F_TSO;

		netdev->features &= ~NETIF_F_TSO6;

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

		for (i = 0; i < adapter->num_tx_queues; i++)

			netif_start_subqueue(netdev, i);

#endif

		netif_start_queue(netdev);

	}

	return 0;

drivers/net/ixgbe/ixgbe_main.c

+0 −40
Original line number Diff line number Diff line
@@ -266,28 +266,16 @@ static bool ixgbe_clean_tx_irq(struct ixgbe_adapter *adapter, 
		 * sees the new next_to_clean.

		 */

		smp_mb();

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

		if (__netif_subqueue_stopped(netdev, tx_ring->queue_index) &&

		    !test_bit(__IXGBE_DOWN, &adapter->state)) {

			netif_wake_subqueue(netdev, tx_ring->queue_index);

			adapter->restart_queue++;

		}

#else

		if (netif_queue_stopped(netdev) &&

		    !test_bit(__IXGBE_DOWN, &adapter->state)) {

			netif_wake_queue(netdev);

			adapter->restart_queue++;

		}

#endif

	}



	if (adapter->detect_tx_hung)

		if (ixgbe_check_tx_hang(adapter, tx_ring, eop, eop_desc))

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

			netif_stop_subqueue(netdev, tx_ring->queue_index);

#else

			netif_stop_queue(netdev);

#endif



	if (total_tx_packets >= tx_ring->work_limit)

		IXGBE_WRITE_REG(&adapter->hw, IXGBE_EICS, tx_ring->eims_value);
@@ -2192,11 +2180,7 @@ static void __devinit ixgbe_set_num_queues(struct ixgbe_adapter *adapter) 
		case (IXGBE_FLAG_RSS_ENABLED):

			rss_m = 0xF;

			nrq = rss_i;

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

			ntq = rss_i;

#else

			ntq = 1;

#endif

			break;

		case 0:

		default:
@@ -2370,10 +2354,8 @@ try_msi: 
	}



out:

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

	/* Notify the stack of the (possibly) reduced Tx Queue count. */

	adapter->netdev->egress_subqueue_count = adapter->num_tx_queues;

#endif



	return err;

}
@@ -2910,9 +2892,7 @@ static void ixgbe_watchdog(unsigned long data) 
	struct net_device *netdev = adapter->netdev;

	bool link_up;

	u32 link_speed = 0;

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

	int i;

#endif



	adapter->hw.mac.ops.check_link(&adapter->hw, &(link_speed), &link_up);
@@ -2934,10 +2914,8 @@ static void ixgbe_watchdog(unsigned long data) 


			netif_carrier_on(netdev);

			netif_wake_queue(netdev);

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

			for (i = 0; i < adapter->num_tx_queues; i++)

				netif_wake_subqueue(netdev, i);

#endif

		} else {

			/* Force detection of hung controller */

			adapter->detect_tx_hung = true;
@@ -3264,11 +3242,7 @@ static int __ixgbe_maybe_stop_tx(struct net_device *netdev, 
{

	struct ixgbe_adapter *adapter = netdev_priv(netdev);



#ifdef CONFIG_NETDEVICES_MULTIQUEUE

	netif_stop_subqueue(netdev, tx_ring->queue_index);

#else

	netif_stop_queue(netdev);

#endif

	/* Herbert's original patch had:

	 *  smp_mb__after_netif_stop_queue();

	 * but since that doesn't exist yet, just open code it. */
@@ -3280,11 +3254,7 @@ static int __ixgbe_maybe_stop_tx(struct net_device *netdev, 
		return -EBUSY;



	/* A reprieve! - use start_queue because it doesn't call schedule */

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

	netif_wake_subqueue(netdev, tx_ring->queue_index);

#else

	netif_wake_queue(netdev);

#endif

	++adapter->restart_queue;

	return 0;

}
@@ -3312,9 +3282,7 @@ static int ixgbe_xmit_frame(struct sk_buff *skb, struct net_device *netdev) 
	unsigned int f;

	unsigned int nr_frags = skb_shinfo(skb)->nr_frags;

	len -= skb->data_len;

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

	r_idx = (adapter->num_tx_queues - 1) & skb->queue_mapping;

#endif

	tx_ring = &adapter->tx_ring[r_idx];
@@ -3502,11 +3470,7 @@ static int __devinit ixgbe_probe(struct pci_dev *pdev, 
	pci_set_master(pdev);

	pci_save_state(pdev);



#ifdef CONFIG_NETDEVICES_MULTIQUEUE

	netdev = alloc_etherdev_mq(sizeof(struct ixgbe_adapter), MAX_TX_QUEUES);

#else

	netdev = alloc_etherdev(sizeof(struct ixgbe_adapter));

#endif

	if (!netdev) {

		err = -ENOMEM;

		goto err_alloc_etherdev;
@@ -3598,9 +3562,7 @@ static int __devinit ixgbe_probe(struct pci_dev *pdev, 
	if (pci_using_dac)

		netdev->features |= NETIF_F_HIGHDMA;



#ifdef CONFIG_NETDEVICES_MULTIQUEUE

	netdev->features |= NETIF_F_MULTI_QUEUE;

#endif



	/* make sure the EEPROM is good */

	if (ixgbe_validate_eeprom_checksum(hw, NULL) < 0) {
@@ -3668,10 +3630,8 @@ static int __devinit ixgbe_probe(struct pci_dev *pdev, 


	netif_carrier_off(netdev);

	netif_stop_queue(netdev);

#ifdef CONFIG_NETDEVICES_MULTIQUEUE

	for (i = 0; i < adapter->num_tx_queues; i++)

		netif_stop_subqueue(netdev, i);

#endif



	ixgbe_napi_add_all(adapter);