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

[Mathieu Desnoyers <compudj@krystal.dyndns.org>]

* Mathieu Desnoyers (compudj@krystal.dyndns.org) wrote:
> * Neil Horman (nhorman@tuxdriver.com) 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@tuxdriver.com>
> > 
> 
> 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@tuxdriver.com>
> >  * Software Engineer, Red Hat
> >  ****************************************************/
> > 
> 
> -- 
> Mathieu Desnoyers
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> 
> _______________________________________________
> ltt-dev mailing list
> ltt-dev@lists.casi.polymtl.ca
> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
> 

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