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Message-Id: <20070822082936.11964.25.sendpatchset@localhost.localdomain>
Date: Wed, 22 Aug 2007 13:59:36 +0530
From: Krishna Kumar <krkumar2@...ibm.com>
To: johnpol@....mipt.ru, herbert@...dor.apana.org.au, hadi@...erus.ca,
kaber@...sh.net, shemminger@...ux-foundation.org,
davem@...emloft.net
Cc: jagana@...ibm.com, Robert.Olsson@...a.slu.se,
peter.p.waskiewicz.jr@...el.com, xma@...ibm.com, gaagaan@...il.com,
kumarkr@...ux.ibm.com, rdreier@...co.com, rick.jones2@...com,
mcarlson@...adcom.com, jeff@...zik.org, mchan@...adcom.com,
general@...ts.openfabrics.org, netdev@...r.kernel.org,
tgraf@...g.ch, Krishna Kumar <krkumar2@...ibm.com>, sri@...ibm.com
Subject: [PATCH 3/10 Rev4] [sched] Modify qdisc_run to support batching
Modify qdisc_run() to support batching. Modify callers of qdisc_run to
use batching, modify qdisc_restart to implement batching.
Signed-off-by: Krishna Kumar <krkumar2@...ibm.com>
---
include/linux/netdevice.h | 2 +
include/net/pkt_sched.h | 6 +--
net/core/dev.c | 44 +++++++++++++++++++++++++++-
net/sched/sch_generic.c | 70 ++++++++++++++++++++++++++++++++++++++--------
4 files changed, 105 insertions(+), 17 deletions(-)
diff -ruNp org/include/net/pkt_sched.h new/include/net/pkt_sched.h
--- org/include/net/pkt_sched.h 2007-08-20 14:26:36.000000000 +0530
+++ new/include/net/pkt_sched.h 2007-08-22 09:23:57.000000000 +0530
@@ -80,13 +80,13 @@ extern struct qdisc_rate_table *qdisc_ge
struct rtattr *tab);
extern void qdisc_put_rtab(struct qdisc_rate_table *tab);
-extern void __qdisc_run(struct net_device *dev);
+extern void __qdisc_run(struct net_device *dev, struct sk_buff_head *blist);
-static inline void qdisc_run(struct net_device *dev)
+static inline void qdisc_run(struct net_device *dev, struct sk_buff_head *blist)
{
if (!netif_queue_stopped(dev) &&
!test_and_set_bit(__LINK_STATE_QDISC_RUNNING, &dev->state))
- __qdisc_run(dev);
+ __qdisc_run(dev, blist);
}
extern int tc_classify_compat(struct sk_buff *skb, struct tcf_proto *tp,
diff -ruNp org/include/linux/netdevice.h new/include/linux/netdevice.h
--- org/include/linux/netdevice.h 2007-08-20 14:26:36.000000000 +0530
+++ new/include/linux/netdevice.h 2007-08-22 08:42:10.000000000 +0530
@@ -892,6 +896,8 @@ extern int dev_set_mac_address(struct n
struct sockaddr *);
extern int dev_hard_start_xmit(struct sk_buff *skb,
struct net_device *dev);
+extern int dev_add_skb_to_blist(struct sk_buff *skb,
+ struct net_device *dev);
extern void dev_init(void);
diff -ruNp org/net/sched/sch_generic.c new/net/sched/sch_generic.c
--- org/net/sched/sch_generic.c 2007-08-20 14:26:37.000000000 +0530
+++ new/net/sched/sch_generic.c 2007-08-22 08:49:55.000000000 +0530
@@ -59,10 +59,12 @@ static inline int qdisc_qlen(struct Qdis
static inline int dev_requeue_skb(struct sk_buff *skb, struct net_device *dev,
struct Qdisc *q)
{
- if (unlikely(skb->next))
- dev->gso_skb = skb;
- else
- q->ops->requeue(skb, q);
+ if (likely(skb)) {
+ if (unlikely(skb->next))
+ dev->gso_skb = skb;
+ else
+ q->ops->requeue(skb, q);
+ }
netif_schedule(dev);
return 0;
@@ -91,10 +93,15 @@ static inline int handle_dev_cpu_collisi
/*
* Same CPU holding the lock. It may be a transient
* configuration error, when hard_start_xmit() recurses. We
- * detect it by checking xmit owner and drop the packet when
- * deadloop is detected. Return OK to try the next skb.
+ * detect it by checking xmit owner and drop the packet (or
+ * all packets in batching case) when deadloop is detected.
+ * Return OK to try the next skb.
*/
- kfree_skb(skb);
+ if (likely(skb))
+ kfree_skb(skb);
+ else if (!skb_queue_empty(dev->skb_blist))
+ skb_queue_purge(dev->skb_blist);
+
if (net_ratelimit())
printk(KERN_WARNING "Dead loop on netdevice %s, "
"fix it urgently!\n", dev->name);
@@ -112,6 +119,38 @@ static inline int handle_dev_cpu_collisi
}
/*
+ * Algorithm to get skb(s) is:
+ * - Non batching drivers, or if the batch list is empty and there is
+ * 1 skb in the queue - dequeue skb and put it in *skbp to tell the
+ * caller to use the single xmit API.
+ * - Batching drivers where the batch list already contains atleast one
+ * skb, or if there are multiple skbs in the queue: keep dequeue'ing
+ * skb's upto a limit and set *skbp to NULL to tell the caller to use
+ * the multiple xmit API.
+ *
+ * Returns:
+ * 1 - atleast one skb is to be sent out, *skbp contains skb or NULL
+ * (in case >1 skbs present in blist for batching)
+ * 0 - no skbs to be sent.
+ */
+static inline int get_skb(struct net_device *dev, struct Qdisc *q,
+ struct sk_buff_head *blist, struct sk_buff **skbp)
+{
+ if (likely(!blist || (!skb_queue_len(blist) && qdisc_qlen(q) <= 1))) {
+ return likely((*skbp = dev_dequeue_skb(dev, q)) != NULL);
+ } else {
+ struct sk_buff *skb;
+ int max = dev->tx_queue_len - skb_queue_len(blist);
+
+ while (max > 0 && (skb = dev_dequeue_skb(dev, q)) != NULL)
+ max -= dev_add_skb_to_blist(skb, dev);
+
+ *skbp = NULL;
+ return 1; /* there is atleast one skb in skb_blist */
+ }
+}
+
+/*
* NOTE: Called under dev->queue_lock with locally disabled BH.
*
* __LINK_STATE_QDISC_RUNNING guarantees only one CPU can process this
@@ -130,7 +169,8 @@ static inline int handle_dev_cpu_collisi
* >0 - queue is not empty.
*
*/
-static inline int qdisc_restart(struct net_device *dev)
+static inline int qdisc_restart(struct net_device *dev,
+ struct sk_buff_head *blist)
{
struct Qdisc *q = dev->qdisc;
struct sk_buff *skb;
@@ -138,7 +178,7 @@ static inline int qdisc_restart(struct n
int ret;
/* Dequeue packet */
- if (unlikely((skb = dev_dequeue_skb(dev, q)) == NULL))
+ if (unlikely(!get_skb(dev, q, blist, &skb)))
return 0;
/*
@@ -168,7 +208,7 @@ static inline int qdisc_restart(struct n
switch (ret) {
case NETDEV_TX_OK:
- /* Driver sent out skb successfully */
+ /* Driver sent out skb (or entire skb_blist) successfully */
ret = qdisc_qlen(q);
break;
@@ -190,10 +230,10 @@ static inline int qdisc_restart(struct n
return ret;
}
-void __qdisc_run(struct net_device *dev)
+void __qdisc_run(struct net_device *dev, struct sk_buff_head *blist)
{
do {
- if (!qdisc_restart(dev))
+ if (!qdisc_restart(dev, blist))
break;
} while (!netif_queue_stopped(dev));
@@ -563,6 +603,12 @@ void dev_deactivate(struct net_device *d
qdisc = dev->qdisc;
dev->qdisc = &noop_qdisc;
+ if (dev->skb_blist) {
+ /* Release skbs on batch list */
+ if (!skb_queue_empty(dev->skb_blist))
+ skb_queue_purge(dev->skb_blist);
+ }
+
qdisc_reset(qdisc);
skb = dev->gso_skb;
diff -ruNp org/net/core/dev.c new/net/core/dev.c
--- org/net/core/dev.c 2007-08-20 14:26:37.000000000 +0530
+++ new/net/core/dev.c 2007-08-22 10:49:22.000000000 +0530
@@ -1466,6 +1466,45 @@ static int dev_gso_segment(struct sk_buf
return 0;
}
+/*
+ * Add skb (skbs in case segmentation is required) to dev->skb_blist. No one
+ * can add to this list simultaneously since we are holding QDISC RUNNING
+ * bit. Also list is safe from simultaneous deletes too since skbs are
+ * dequeued only when the driver is invoked.
+ *
+ * Returns count of successful skb(s) added to skb_blist.
+ */
+int dev_add_skb_to_blist(struct sk_buff *skb, struct net_device *dev)
+{
+ if (!list_empty(&ptype_all))
+ dev_queue_xmit_nit(skb, dev);
+
+ if (netif_needs_gso(dev, skb)) {
+ if (unlikely(dev_gso_segment(skb))) {
+ kfree(skb);
+ return 0;
+ }
+
+ if (skb->next) {
+ int count = 0;
+
+ do {
+ struct sk_buff *nskb = skb->next;
+
+ skb->next = nskb->next;
+ __skb_queue_tail(dev->skb_blist, nskb);
+ count++;
+ } while (skb->next);
+
+ skb->destructor = DEV_GSO_CB(skb)->destructor;
+ kfree_skb(skb);
+ return count;
+ }
+ }
+ __skb_queue_tail(dev->skb_blist, skb);
+ return 1;
+}
+
int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
if (likely(skb)) {
@@ -1620,7 +1659,7 @@ gso:
/* reset queue_mapping to zero */
skb->queue_mapping = 0;
rc = q->enqueue(skb, q);
- qdisc_run(dev);
+ qdisc_run(dev, NULL);
spin_unlock(&dev->queue_lock);
rc = rc == NET_XMIT_BYPASS ? NET_XMIT_SUCCESS : rc;
@@ -1818,7 +1857,8 @@ static void net_tx_action(struct softirq
clear_bit(__LINK_STATE_SCHED, &dev->state);
if (spin_trylock(&dev->queue_lock)) {
- qdisc_run(dev);
+ /* Send all skbs if driver supports batching */
+ qdisc_run(dev, dev->skb_blist);
spin_unlock(&dev->queue_lock);
} else {
netif_schedule(dev);
-
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