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Date: Tue, 20 Jul 2010 15:47:53 +0900 From: Koki Sanagi <sanagi.koki@...fujitsu.com> To: Eric Dumazet <eric.dumazet@...il.com> CC: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, davem@...emloft.net, kaneshige.kenji@...fujitsu.com, izumi.taku@...fujitsu.com, kosaki.motohiro@...fujitsu.com, nhorman@...driver.com, laijs@...fujitsu.com, scott.a.mcmillan@...el.com, rostedt@...dmis.org, fweisbec@...il.com, mathieu.desnoyers@...ymtl.ca Subject: Re: [RFC PATCH v3 4/5] skb: add tracepoints to freeing skb (2010/07/20 13:54), Eric Dumazet wrote: > Le mardi 20 juillet 2010 à 09:49 +0900, Koki Sanagi a écrit : >> [RFC PATCH v3 4/5] skb: add tracepoints to freeing skb >> This patch adds tracepoint to consume_skb, dev_kfree_skb_irq and >> skb_free_datagram_locked. Combinating with tracepoint on dev_hard_start_xmit, >> we can check how long it takes to free transmited packets. And using it, we can >> calculate how many packets driver had at that time. It is useful when a drop of >> transmited packet is a problem. >> >> <idle>-0 [001] 241409.218333: consume_skb: skbaddr=dd6b2fb8 >> <idle>-0 [001] 241409.490555: dev_kfree_skb_irq: skbaddr=f5e29840 >> >> udp-recv-302 [001] 515031.206008: skb_free_datagram_locked: skbaddr=f5b1d900 >> >> >> Signed-off-by: Koki Sanagi <sanagi.koki@...fujitsu.com> >> --- >> include/trace/events/skb.h | 42 ++++++++++++++++++++++++++++++++++++++++++ >> net/core/datagram.c | 1 + >> net/core/dev.c | 2 ++ >> net/core/skbuff.c | 1 + >> 4 files changed, 46 insertions(+), 0 deletions(-) >> >> diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h >> index 4b2be6d..84c9041 100644 >> --- a/include/trace/events/skb.h >> +++ b/include/trace/events/skb.h >> @@ -35,6 +35,48 @@ TRACE_EVENT(kfree_skb, >> __entry->skbaddr, __entry->protocol, __entry->location) >> ); >> >> +DECLARE_EVENT_CLASS(free_skb, >> + >> + TP_PROTO(struct sk_buff *skb), >> + >> + TP_ARGS(skb), >> + >> + TP_STRUCT__entry( >> + __field( void *, skbaddr ) >> + ), >> + >> + TP_fast_assign( >> + __entry->skbaddr = skb; >> + ), >> + >> + TP_printk("skbaddr=%p", __entry->skbaddr) >> + >> +); >> + >> +DEFINE_EVENT(free_skb, consume_skb, >> + >> + TP_PROTO(struct sk_buff *skb), >> + >> + TP_ARGS(skb) >> + >> +); >> + >> +DEFINE_EVENT(free_skb, dev_kfree_skb_irq, >> + >> + TP_PROTO(struct sk_buff *skb), >> + >> + TP_ARGS(skb) >> + >> +); >> + >> +DEFINE_EVENT(free_skb, skb_free_datagram_locked, >> + >> + TP_PROTO(struct sk_buff *skb), >> + >> + TP_ARGS(skb) >> + >> +); >> + >> TRACE_EVENT(skb_copy_datagram_iovec, >> >> TP_PROTO(const struct sk_buff *skb, int len), >> diff --git a/net/core/datagram.c b/net/core/datagram.c >> index f5b6f43..1ea32a0 100644 >> --- a/net/core/datagram.c >> +++ b/net/core/datagram.c >> @@ -231,6 +231,7 @@ void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb) >> { >> bool slow; >> >> + trace_skb_free_datagram_locked(skb); > > Here you unconditionally trace before the test on skb->users > >> if (likely(atomic_read(&skb->users) == 1)) >> smp_rmb(); >> else if (likely(!atomic_dec_and_test(&skb->users))) >> diff --git a/net/core/dev.c b/net/core/dev.c >> index 4acfec6..d979847 100644 >> --- a/net/core/dev.c >> +++ b/net/core/dev.c >> @@ -131,6 +131,7 @@ >> #include <linux/random.h> >> #include <trace/events/napi.h> >> #include <trace/events/net.h> >> +#include <trace/events/skb.h> >> #include <linux/pci.h> >> >> #include "net-sysfs.h" >> @@ -1581,6 +1582,7 @@ void dev_kfree_skb_irq(struct sk_buff *skb) >> struct softnet_data *sd; >> unsigned long flags; >> >> + trace_dev_kfree_skb_irq(skb); >> local_irq_save(flags); >> sd = &__get_cpu_var(softnet_data); >> skb->next = sd->completion_queue; >> diff --git a/net/core/skbuff.c b/net/core/skbuff.c >> index 34432b4..a7b4036 100644 >> --- a/net/core/skbuff.c >> +++ b/net/core/skbuff.c >> @@ -466,6 +466,7 @@ void consume_skb(struct sk_buff *skb) >> smp_rmb(); >> else if (likely(!atomic_dec_and_test(&skb->users))) >> return; > > While here you trace _after_ the test on skb->users - and a "return;" , > so you miss some consume_skb() calls > Yeah, I'll move trace_consume_skb() before the test. Thanks, Koki Sanagi. > >> + trace_consume_skb(skb); >> __kfree_skb(skb); >> } >> EXPORT_SYMBOL(consume_skb); >> > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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