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authorPaolo Abeni <pabeni@redhat.com>2019-04-10 14:32:40 +0200
committerDavid S. Miller <davem@davemloft.net>2019-04-10 12:20:46 -0700
commit8a53e616de294873fec1a75ddb77ecb3d225cee0 (patch)
tree417d298678e0f2bba183375d0754ff2f8ccbe19e
parentnet: sched: always do stats accounting according to TCQ_F_CPUSTATS (diff)
downloadlinux-dev-8a53e616de294873fec1a75ddb77ecb3d225cee0.tar.xz
linux-dev-8a53e616de294873fec1a75ddb77ecb3d225cee0.zip
net: sched: when clearing NOLOCK, clear TCQ_F_CPUSTATS, too
Since stats updating is always consistent with TCQ_F_CPUSTATS flag, we can disable it at qdisc creation time flipping such bit. In my experiments, if the NOLOCK flag is cleared, per CPU stats accounting does not give any measurable performance gain, but it waste some memory. Let's clear TCQ_F_CPUSTATS together with NOLOCK, when enslaving a NOLOCK qdisc to 'lock' one. Use stats update helper inside pfifo_fast, to cope correctly with TCQ_F_CPUSTATS flag change. As a side effect, q.qlen value for any child qdiscs is always consistent for all lock classfull qdiscs. Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/sch_generic.h26
-rw-r--r--net/sched/sch_api.c15
-rw-r--r--net/sched/sch_generic.c10
3 files changed, 42 insertions, 9 deletions
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index ed56474cfe3b..f069011524ba 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -1106,6 +1106,32 @@ static inline struct sk_buff *qdisc_peek_dequeued(struct Qdisc *sch)
return skb;
}
+static inline void qdisc_update_stats_at_dequeue(struct Qdisc *sch,
+ struct sk_buff *skb)
+{
+ if (qdisc_is_percpu_stats(sch)) {
+ qdisc_qstats_cpu_backlog_dec(sch, skb);
+ qdisc_bstats_cpu_update(sch, skb);
+ qdisc_qstats_atomic_qlen_dec(sch);
+ } else {
+ qdisc_qstats_backlog_dec(sch, skb);
+ qdisc_bstats_update(sch, skb);
+ sch->q.qlen--;
+ }
+}
+
+static inline void qdisc_update_stats_at_enqueue(struct Qdisc *sch,
+ unsigned int pkt_len)
+{
+ if (qdisc_is_percpu_stats(sch)) {
+ qdisc_qstats_atomic_qlen_inc(sch);
+ this_cpu_add(sch->cpu_qstats->backlog, pkt_len);
+ } else {
+ sch->qstats.backlog += pkt_len;
+ sch->q.qlen++;
+ }
+}
+
/* use instead of qdisc->dequeue() for all qdiscs queried with ->peek() */
static inline struct sk_buff *qdisc_dequeue_peeked(struct Qdisc *sch)
{
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index fb8f138b9776..c126b9f78d6e 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -998,6 +998,19 @@ static void notify_and_destroy(struct net *net, struct sk_buff *skb,
qdisc_put(old);
}
+static void qdisc_clear_nolock(struct Qdisc *sch)
+{
+ sch->flags &= ~TCQ_F_NOLOCK;
+ if (!(sch->flags & TCQ_F_CPUSTATS))
+ return;
+
+ free_percpu(sch->cpu_bstats);
+ free_percpu(sch->cpu_qstats);
+ sch->cpu_bstats = NULL;
+ sch->cpu_qstats = NULL;
+ sch->flags &= ~TCQ_F_CPUSTATS;
+}
+
/* Graft qdisc "new" to class "classid" of qdisc "parent" or
* to device "dev".
*
@@ -1076,7 +1089,7 @@ skip:
/* Only support running class lockless if parent is lockless */
if (new && (new->flags & TCQ_F_NOLOCK) &&
parent && !(parent->flags & TCQ_F_NOLOCK))
- new->flags &= ~TCQ_F_NOLOCK;
+ qdisc_clear_nolock(new);
if (!cops || !cops->graft)
return -EOPNOTSUPP;
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index ddff2952be87..12a6e1a39fa0 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -629,11 +629,7 @@ static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
if (unlikely(err))
return qdisc_drop_cpu(skb, qdisc, to_free);
- qdisc_qstats_atomic_qlen_inc(qdisc);
- /* Note: skb can not be used after skb_array_produce(),
- * so we better not use qdisc_qstats_cpu_backlog_inc()
- */
- this_cpu_add(qdisc->cpu_qstats->backlog, pkt_len);
+ qdisc_update_stats_at_enqueue(qdisc, pkt_len);
return NET_XMIT_SUCCESS;
}
@@ -652,9 +648,7 @@ static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
skb = __skb_array_consume(q);
}
if (likely(skb)) {
- qdisc_qstats_cpu_backlog_dec(qdisc, skb);
- qdisc_bstats_cpu_update(qdisc, skb);
- qdisc_qstats_atomic_qlen_dec(qdisc);
+ qdisc_update_stats_at_dequeue(qdisc, skb);
} else {
qdisc->empty = true;
}