Subject: Re: [patch 37/37] LTTng instrumentation net

From: Mathieu Desnoyers <[email-masked]>
Date: Thu, 24 Apr 2008 12:13:37 -0400

* Pavel Emelyanov ([email-masked]) wrote:
> Mathieu Desnoyers wrote:
> > Network core events.
> > 
> > Added markers :
> > 
> > net_del_ifa_ipv4
> > net_dev_receive
> > net_dev_xmit
> > net_insert_ifa_ipv4
> > net_socket_call
> > net_socket_create
> > net_socket_recvmsg
> > net_socket_sendmsg
> 
> Network "core" events are not limited with the above calls.
> 

True. This is by no mean an exhaustive list of network events. It just
happens to be the ones which has been useful to LTT/LTTng users for the
past ~10 years.

> Besides, real "core" events already sent notifications about themselves.
> Why do we need additional hooks?
> 

I doubt the current notification hooks have a performance impact as
small as the proposed markers. Which notification mechanism do you refer
to ? It could be interesting to put markers in there instead.

The goal behind this is to feed information to a general purpose tracer
like lttng, a scripting mechanism like systemtap or a special-purpose
tracer like ftrace.

I think that the most important instrumentation in this patchset is the
xmit/recv of a packet at the device level. The net_socket_*
instrumentation could eventually be replaced by an architecture specfic
system call parameters instrumentation.

Mathieu

> > Signed-off-by: Mathieu Desnoyers <[email-masked]>
> > CC: [email-masked]
> > ---
> >  net/core/dev.c     |    6 ++++++
> >  net/ipv4/devinet.c |    6 ++++++
> >  net/socket.c       |   19 +++++++++++++++++++
> >  3 files changed, 31 insertions(+)
> 

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68