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Commit b2268830 authored by Stefan Richter's avatar Stefan Richter
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firewire: net: throttle TX queue before running out of tlabels 



This prevents firewire-net from submitting write requests in fast
succession until failure due to all 64 transaction labels were used up
for unfinished split transactions.  The netif_stop/wake_queue API is
used for this purpose.

Without this stop/wake mechanism, datagrams were simply lost whenever
the tlabel pool was exhausted.  Plus, tlabel exhaustion by firewire-net
also prevented other unrelated outbound transactions to be initiated.

The chosen queue depth was checked by me to hit the maximum possible
throughput with an OS X peer whose receive DMA is good enough to never
reject requests due to busy inbound request FIFO.  Current Linux peers
show a mixed picture of -5%...+15% change in bandwidth; their current
bottleneck are RCODE_BUSY situations (fewer or more, depending on TX
queue depth) due to too small AR buffer in firewire-ohci.

Maxim Levitsky tested this change with similar watermarks with a Linux
peer and some pending firewire-ohci improvements that address the
RCODE_BUSY problem and confirmed that these TX queue limits are good.

Note:  This removes some netif_wake_queue from reception code paths.
They were apparently copy&paste artefacts from a nonsensical
netif_wake_queue use in the older eth1394 driver.  This belongs only
into the transmit path.

Signed-off-by: default avatarStefan Richter <stefanr@s5r6.in-berlin.de>
Tested-by: default avatarMaxim Levitsky <maximlevitsky@gmail.com>
parent 48553011

drivers/firewire/net.c

+35 −24
Original line number Original line Diff line number Diff line
@@ -27,9 +27,15 @@ 
#include <asm/unaligned.h>

#include <asm/unaligned.h>

#include <net/arp.h>

#include <net/arp.h>





#define FWNET_MAX_FRAGMENTS	25	/* arbitrary limit */

/* rx limits */

#define FWNET_MAX_FRAGMENTS		30 /* arbitrary, > TX queue depth */

#define FWNET_ISO_PAGE_COUNT		(PAGE_SIZE < 16*1024 ? 4 : 2)

#define FWNET_ISO_PAGE_COUNT		(PAGE_SIZE < 16*1024 ? 4 : 2)





/* tx limits */

#define FWNET_MAX_QUEUED_DATAGRAMS	20 /* < 64 = number of tlabels */

#define FWNET_MIN_QUEUED_DATAGRAMS	10 /* should keep AT DMA busy enough */

#define FWNET_TX_QUEUE_LEN		FWNET_MAX_QUEUED_DATAGRAMS /* ? */



#define IEEE1394_BROADCAST_CHANNEL	31

#define IEEE1394_BROADCAST_CHANNEL	31

#define IEEE1394_ALL_NODES		(0xffc0 | 0x003f)

#define IEEE1394_ALL_NODES		(0xffc0 | 0x003f)

#define IEEE1394_MAX_PAYLOAD_S100	512

#define IEEE1394_MAX_PAYLOAD_S100	512
@@ -640,8 +646,6 @@ static int fwnet_finish_incoming_packet(struct net_device *net, 
		net->stats.rx_packets++;

		net->stats.rx_packets++;

		net->stats.rx_bytes += skb->len;

		net->stats.rx_bytes += skb->len;

	}

	}

	if (netif_queue_stopped(net))

		netif_wake_queue(net);





	return 0;

	return 0;
@@ -650,8 +654,6 @@ static int fwnet_finish_incoming_packet(struct net_device *net, 
	net->stats.rx_dropped++;

	net->stats.rx_dropped++;





	dev_kfree_skb_any(skb);

	dev_kfree_skb_any(skb);

	if (netif_queue_stopped(net))

		netif_wake_queue(net);





	return -ENOENT;

	return -ENOENT;

}

}
@@ -783,15 +785,10 @@ static int fwnet_incoming_packet(struct fwnet_device *dev, __be32 *buf, int len, 
	 * Datagram is not complete, we're done for the

	 * Datagram is not complete, we're done for the

	 * moment.

	 * moment.

	 */

	 */

	spin_unlock_irqrestore(&dev->lock, flags);

	retval = 0;



	return 0;

 fail:

 fail:

	spin_unlock_irqrestore(&dev->lock, flags);

	spin_unlock_irqrestore(&dev->lock, flags);





	if (netif_queue_stopped(net))

		netif_wake_queue(net);



	return retval;

	return retval;

}

}
@@ -891,6 +888,13 @@ static void fwnet_free_ptask(struct fwnet_packet_task *ptask) 
	kmem_cache_free(fwnet_packet_task_cache, ptask);

	kmem_cache_free(fwnet_packet_task_cache, ptask);

}

}





/* Caller must hold dev->lock. */

static void dec_queued_datagrams(struct fwnet_device *dev)

{

	if (--dev->queued_datagrams == FWNET_MIN_QUEUED_DATAGRAMS)

		netif_wake_queue(dev->netdev);

}



static int fwnet_send_packet(struct fwnet_packet_task *ptask);

static int fwnet_send_packet(struct fwnet_packet_task *ptask);





static void fwnet_transmit_packet_done(struct fwnet_packet_task *ptask)

static void fwnet_transmit_packet_done(struct fwnet_packet_task *ptask)
@@ -907,7 +911,7 @@ static void fwnet_transmit_packet_done(struct fwnet_packet_task *ptask) 
	/* Check whether we or the networking TX soft-IRQ is last user. */

	/* Check whether we or the networking TX soft-IRQ is last user. */

	free = (ptask->outstanding_pkts == 0 && ptask->enqueued);

	free = (ptask->outstanding_pkts == 0 && ptask->enqueued);

	if (free)

	if (free)

		dev->queued_datagrams--;

		dec_queued_datagrams(dev);





	if (ptask->outstanding_pkts == 0) {

	if (ptask->outstanding_pkts == 0) {

		dev->netdev->stats.tx_packets++;

		dev->netdev->stats.tx_packets++;
@@ -978,7 +982,7 @@ static void fwnet_transmit_packet_failed(struct fwnet_packet_task *ptask) 
	/* Check whether we or the networking TX soft-IRQ is last user. */

	/* Check whether we or the networking TX soft-IRQ is last user. */

	free = ptask->enqueued;

	free = ptask->enqueued;

	if (free)

	if (free)

		dev->queued_datagrams--;

		dec_queued_datagrams(dev);





	dev->netdev->stats.tx_dropped++;

	dev->netdev->stats.tx_dropped++;

	dev->netdev->stats.tx_errors++;

	dev->netdev->stats.tx_errors++;
@@ -1063,7 +1067,7 @@ static int fwnet_send_packet(struct fwnet_packet_task *ptask) 
		if (!free)

		if (!free)

			ptask->enqueued = true;

			ptask->enqueued = true;

		else

		else

			dev->queued_datagrams--;

			dec_queued_datagrams(dev);





		spin_unlock_irqrestore(&dev->lock, flags);

		spin_unlock_irqrestore(&dev->lock, flags);
@@ -1082,7 +1086,7 @@ static int fwnet_send_packet(struct fwnet_packet_task *ptask) 
	if (!free)

	if (!free)

		ptask->enqueued = true;

		ptask->enqueued = true;

	else

	else

		dev->queued_datagrams--;

		dec_queued_datagrams(dev);





	spin_unlock_irqrestore(&dev->lock, flags);

	spin_unlock_irqrestore(&dev->lock, flags);
@@ -1248,6 +1252,15 @@ static netdev_tx_t fwnet_tx(struct sk_buff *skb, struct net_device *net) 
	struct fwnet_peer *peer;

	struct fwnet_peer *peer;

	unsigned long flags;

	unsigned long flags;





	spin_lock_irqsave(&dev->lock, flags);



	/* Can this happen? */

	if (netif_queue_stopped(dev->netdev)) {

		spin_unlock_irqrestore(&dev->lock, flags);



		return NETDEV_TX_BUSY;

	}



	ptask = kmem_cache_alloc(fwnet_packet_task_cache, GFP_ATOMIC);

	ptask = kmem_cache_alloc(fwnet_packet_task_cache, GFP_ATOMIC);

	if (ptask == NULL)

	if (ptask == NULL)

		goto fail;

		goto fail;
@@ -1266,9 +1279,6 @@ static netdev_tx_t fwnet_tx(struct sk_buff *skb, struct net_device *net) 
	proto = hdr_buf.h_proto;

	proto = hdr_buf.h_proto;

	dg_size = skb->len;

	dg_size = skb->len;





	/* serialize access to peer, including peer->datagram_label */

	spin_lock_irqsave(&dev->lock, flags);



	/*

	/*

	 * Set the transmission type for the packet.  ARP packets and IP

	 * Set the transmission type for the packet.  ARP packets and IP

	 * broadcast packets are sent via GASP.

	 * broadcast packets are sent via GASP.
@@ -1290,7 +1300,7 @@ static netdev_tx_t fwnet_tx(struct sk_buff *skb, struct net_device *net) 




		peer = fwnet_peer_find_by_guid(dev, be64_to_cpu(guid));

		peer = fwnet_peer_find_by_guid(dev, be64_to_cpu(guid));

		if (!peer || peer->fifo == FWNET_NO_FIFO_ADDR)

		if (!peer || peer->fifo == FWNET_NO_FIFO_ADDR)

			goto fail_unlock;

			goto fail;





		generation         = peer->generation;

		generation         = peer->generation;

		dest_node          = peer->node_id;

		dest_node          = peer->node_id;
@@ -1344,7 +1354,8 @@ static netdev_tx_t fwnet_tx(struct sk_buff *skb, struct net_device *net) 
		max_payload += RFC2374_FRAG_HDR_SIZE;

		max_payload += RFC2374_FRAG_HDR_SIZE;

	}

	}





	dev->queued_datagrams++;

	if (++dev->queued_datagrams == FWNET_MAX_QUEUED_DATAGRAMS)

		netif_stop_queue(dev->netdev);





	spin_unlock_irqrestore(&dev->lock, flags);

	spin_unlock_irqrestore(&dev->lock, flags);
@@ -1355,9 +1366,9 @@ static netdev_tx_t fwnet_tx(struct sk_buff *skb, struct net_device *net) 




	return NETDEV_TX_OK;

	return NETDEV_TX_OK;





 fail_unlock:

	spin_unlock_irqrestore(&dev->lock, flags);

 fail:

 fail:

	spin_unlock_irqrestore(&dev->lock, flags);



	if (ptask)

	if (ptask)

		kmem_cache_free(fwnet_packet_task_cache, ptask);

		kmem_cache_free(fwnet_packet_task_cache, ptask);
@@ -1403,7 +1414,7 @@ static void fwnet_init_dev(struct net_device *net) 
	net->addr_len		= FWNET_ALEN;

	net->addr_len		= FWNET_ALEN;

	net->hard_header_len	= FWNET_HLEN;

	net->hard_header_len	= FWNET_HLEN;

	net->type		= ARPHRD_IEEE1394;

	net->type		= ARPHRD_IEEE1394;

	net->tx_queue_len	= 10;

	net->tx_queue_len	= FWNET_TX_QUEUE_LEN;

}

}





/* caller must hold fwnet_device_mutex */

/* caller must hold fwnet_device_mutex */