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Message-ID: <20080424161337.GA22874@Krystal>
Date: Thu, 24 Apr 2008 12:13:37 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To: Pavel Emelyanov <xemul@...nvz.org>
Cc: akpm@...ux-foundation.org, Ingo Molnar <mingo@...e.hu>,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [patch 37/37] LTTng instrumentation net
* Pavel Emelyanov (xemul@...nvz.org) 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 <mathieu.desnoyers@...ymtl.ca>
> > CC: netdev@...r.kernel.org
> > ---
> > 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
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