path: root/drivers/net/ppp/ppp_generic.c
diff options
authorDavid Woodhouse <dwmw2@infradead.org>2012-03-26 00:03:42 +0000
committerDavid S. Miller <davem@davemloft.net>2012-04-03 17:31:38 -0400
commite675f0cc9a872fd152edc0c77acfed19bf28b81e (patch)
tree244c4488575cc19bd882ad00c2d6852db5bcbe98 /drivers/net/ppp/ppp_generic.c
parentnet: fix /proc/net/dev regression (diff)
ppp: Don't stop and restart queue on every TX packet
For every transmitted packet, ppp_start_xmit() will stop the netdev queue and then, if appropriate, restart it. This causes the TX softirq to run, entirely gratuitously. This is "only" a waste of CPU time in the normal case, but it's actively harmful when the PPP device is a TEQL slave — the wakeup will cause the offending device to receive the next TX packet from the TEQL queue, when it *should* have gone to the next slave in the list. We end up seeing large bursts of packets on just *one* slave device, rather than using the full available bandwidth over all slaves. This patch fixes the problem by *not* unconditionally stopping the queue in ppp_start_xmit(). It adds a return value from ppp_xmit_process() which indicates whether the queue should be stopped or not. It *doesn't* remove the call to netif_wake_queue() from ppp_xmit_process(), because other code paths (especially from ppp_output_wakeup()) need it there and it's messy to push it out to the other callers to do it based on the return value. So we leave it in place — it's a no-op in the case where the queue wasn't stopped, so it's harmless in the TX path. Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ppp/ppp_generic.c')
1 files changed, 9 insertions, 5 deletions
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 159da2905fe9..33f8c51968b6 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -235,7 +235,7 @@ struct ppp_net {
/* Prototypes. */
static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
struct file *file, unsigned int cmd, unsigned long arg);
-static void ppp_xmit_process(struct ppp *ppp);
+static int ppp_xmit_process(struct ppp *ppp);
static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
static void ppp_push(struct ppp *ppp);
static void ppp_channel_push(struct channel *pch);
@@ -968,9 +968,9 @@ ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
proto = npindex_to_proto[npi];
put_unaligned_be16(proto, pp);
- netif_stop_queue(dev);
skb_queue_tail(&ppp->file.xq, skb);
- ppp_xmit_process(ppp);
+ if (!ppp_xmit_process(ppp))
+ netif_stop_queue(dev);
return NETDEV_TX_OK;
@@ -1048,10 +1048,11 @@ static void ppp_setup(struct net_device *dev)
* Called to do any work queued up on the transmit side
* that can now be done.
-static void
+static int
ppp_xmit_process(struct ppp *ppp)
struct sk_buff *skb;
+ int ret = 0;
if (!ppp->closing) {
@@ -1061,10 +1062,13 @@ ppp_xmit_process(struct ppp *ppp)
ppp_send_frame(ppp, skb);
/* If there's no work left to do, tell the core net
code that we can accept some more. */
- if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
+ if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq)) {
+ ret = 1;
+ }
+ return ret;
static inline struct sk_buff *