Re: [ltt-dev] [PATCH] add tracepoints to track change in napistates on network receive

From: Mathieu Desnoyers
Date: Wed Dec 03 2008 - 13:21:46 EST

* Mathieu Desnoyers (compudj@xxxxxxxxxxxxxxxxxx) wrote:
> * Neil Horman (nhorman@xxxxxxxxxxxxx) wrote:
> > On Wed, Dec 03, 2008 at 12:25:07PM -0500, Mathieu Desnoyers wrote:
> > > Almost there :)
> > >
> > > There is a extra whitespace above,
> > >
> > > and also "schedule napi_struct" should probably be changed into
> > > napi_struct only, this removes the whitespace and duplicated information
> > > (I guess we know that given we are in event net_napi_schedule, this will
> > > have something to do with schedule...). Same applies to trace_mark_tp
> > > below.
> > >
> > > Thanks,
> > >
> > > Mathieu
> >
> >
> > Sure, here you go, new patch
> >
> > Patch to trace napi states for various net devices and their napi instances.
> > Traces scheduling, servicing and completion of a napi poll request.
> >
> > Regards
> > Neil
> >
> > Signed-off-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
> >
>
> Actually I notice that you used the old "DEFINE_TRACE" tracepoint API.

The patch has been edited and folded into
lttng-instrumentation-net.patch
lttng-instrumentation-net-tracepoints-probes.patch

Mathieu

> I'll update your patch to the new DECLARE/DEFINE_TRACE tracepoint API.
>
> Mathieu
>
> >
> > include/linux/netdevice.h | 5 +++++
> > include/trace/netdevice.h | 30 ++++++++++++++++++++++++++++++
> > ltt/probes/net-trace.c | 22 ++++++++++++++++++++++
> > net/core/dev.c | 7 ++++++-
> > 4 files changed, 63 insertions(+), 1 deletion(-)
> >
> >
> > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> > index 488c56e..7da71eb 100644
> > --- a/include/linux/netdevice.h
> > +++ b/include/linux/netdevice.h
> > @@ -43,6 +43,9 @@
> >
> > #include <net/net_namespace.h>
> >
> > +struct napi_struct;
> > +#include <trace/netdevice.h>
> > +
> > struct vlan_group;
> > struct ethtool_ops;
> > struct netpoll_info;
> > @@ -386,6 +389,7 @@ static inline void napi_complete(struct napi_struct *n)
> > local_irq_save(flags);
> > __napi_complete(n);
> > local_irq_restore(flags);
> > + trace_napi_complete(n);
> > }
> >
> > /**
> > @@ -1726,6 +1730,7 @@ static inline int skb_bond_should_drop(struct sk_buff *skb)
> > return 0;
> > }
> >
> > +
> > #endif /* __KERNEL__ */
> >
> > #endif /* _LINUX_DEV_H */
> > diff --git a/include/trace/netdevice.h b/include/trace/netdevice.h
> > new file mode 100644
> > index 0000000..ba48f6c
> > --- /dev/null
> > +++ b/include/trace/netdevice.h
> > @@ -0,0 +1,30 @@
> > +#ifndef _INCLUDE_NETDEVICE_H_
> > +#define _INCLUDE_NETDEVICE_H_
> > +
> > +#include <linux/netdevice.h>
> > +
> > +/* Tracepoints */
> > +
> > +/*
> > + * Note these first 2 traces are actually in __napi_schedule and net_rx_action
> > + * respectively. The former is in __napi_schedule because it uses at-most-once
> > + * logic and placing it in the calling routine (napi_schedule) would produce
> > + * countless trace events that were effectively no-ops. napi_poll is
> > + * implemented in net_rx_action, because thats where we do our polling on
> > + * devices. The last trace point is in napi_complete, right where you would
> > + * think it would be.
> > + */
> > +DEFINE_TRACE(napi_schedule,
> > + TPPROTO(struct napi_struct *n),
> > + TPARGS(n));
> > +
> > +DEFINE_TRACE(napi_poll,
> > + TPPROTO(struct napi_struct *n),
> > + TPARGS(n));
> > +
> > +DEFINE_TRACE(napi_complete,
> > + TPPROTO(struct napi_struct *n),
> > + TPARGS(n));
> > +
> > +#endif
> > +
> > diff --git a/ltt/probes/net-trace.c b/ltt/probes/net-trace.c
> > index bac2b21..e887e70 100644
> > --- a/ltt/probes/net-trace.c
> > +++ b/ltt/probes/net-trace.c
> > @@ -9,6 +9,7 @@
> > #include <trace/ipv4.h>
> > #include <trace/ipv6.h>
> > #include <trace/socket.h>
> > +#include <trace/netdevice.h>
> >
> > void probe_net_dev_xmit(struct sk_buff *skb)
> > {
> > @@ -104,6 +105,27 @@ void probe_socket_call(int call, unsigned long a0)
> > "call %d a0 %lu", call, a0);
> > }
> >
> > +void probe_napi_schedule(struct napi_struct *n)
> > +{
> > + trace_mark_tp(net_napi_schedule, napi_schedule, probe_napi_schedule,
> > + "napi_struct %p name %s",
> > + n, n->dev->name);
> > +}
> > +
> > +void probe_napi_poll(struct napi_struct *n)
> > +{
> > + trace_mark_tp(net_napi_poll, napi_poll, probe_napi_poll,
> > + "napi_struct %p name %s",
> > + n, n->dev->name);
> > +}
> > +
> > +void probe_napi_complete(struct napi_struct *n)
> > +{
> > + trace_mark_tp(net_napi_complete, napi_complete, probe_napi_complete,
> > + "napi_struct %p name %s",
> > + n, n->dev->name);
> > +}
> > +
> > MODULE_LICENSE("GPL");
> > MODULE_AUTHOR("Mathieu Desnoyers");
> > MODULE_DESCRIPTION("Net Tracepoint Probes");
> > diff --git a/net/core/dev.c b/net/core/dev.c
> > index 836fe6e..0c55c0f 100644
> > --- a/net/core/dev.c
> > +++ b/net/core/dev.c
> > @@ -128,6 +128,7 @@
> > #include <linux/jhash.h>
> > #include <linux/random.h>
> > #include <trace/net.h>
> > +#include <trace/netdevice.h>
> >
> > #include "net-sysfs.h"
> >
> > @@ -2329,6 +2330,8 @@ void __napi_schedule(struct napi_struct *n)
> > {
> > unsigned long flags;
> >
> > + trace_napi_poll(n);
> > +
> > local_irq_save(flags);
> > list_add_tail(&n->poll_list, &__get_cpu_var(softnet_data).poll_list);
> > __raise_softirq_irqoff(NET_RX_SOFTIRQ);
> > @@ -2380,8 +2383,10 @@ static void net_rx_action(struct softirq_action *h)
> > * accidently calling ->poll() when NAPI is not scheduled.
> > */
> > work = 0;
> > - if (test_bit(NAPI_STATE_SCHED, &n->state))
> > + if (test_bit(NAPI_STATE_SCHED, &n->state)) {
> > + trace_napi_poll(n);
> > work = n->poll(n, weight);
> > + }
> >
> > WARN_ON_ONCE(work > weight);
> >
> > --
> > /****************************************************
> > * Neil Horman <nhorman@xxxxxxxxxxxxx>
> > * Software Engineer, Red Hat
> > ****************************************************/
> >
>
> --
> Mathieu Desnoyers
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
>
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> ltt-dev mailing list
> ltt-dev@xxxxxxxxxxxxxxxxxxxxx
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>

--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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