diff mbox

[RFC,07/12] net: sched: qdisc_qlen for per cpu logic

Message ID 20151230175335.26257.34457.stgit@john-Precision-Tower-5810
State RFC, archived
Delegated to: David Miller
Headers show

Commit Message

John Fastabend Dec. 30, 2015, 5:53 p.m. UTC
This is a bit interesting because it means sch_direct_xmit will
return a positive value which causes the dequeue/xmit cycle to
continue only when a specific cpu has a qlen > 0.

However checking each cpu for qlen will break performance so
its important to note that qdiscs that set the no lock bit need
to have some sort of per cpu enqueue/dequeue data structure that
maps to the per cpu qlen value.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
---
 include/net/sch_generic.h |    8 ++++++++
 1 file changed, 8 insertions(+)


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diff mbox

Patch

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index aa39dd4..30f4c60 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -273,8 +273,16 @@  static inline void qdisc_cb_private_validate(const struct sk_buff *skb, int sz)
 	BUILD_BUG_ON(sizeof(qcb->data) < sz);
 }
 
+static inline int qdisc_qlen_cpu(const struct Qdisc *q)
+{
+	return this_cpu_ptr(q->cpu_qstats)->qlen;
+}
+
 static inline int qdisc_qlen(const struct Qdisc *q)
 {
+	if (q->flags & TCQ_F_NOLOCK)
+		return qdisc_qlen_cpu(q);
+
 	return q->q.qlen;
 }