[Beowulf] raw ethernet

050675 at student.unife.it 050675 at student.unife.it
Fri Jul 23 00:04:22 PDT 2004

Hi all, I've seen yours mails in response to my first post about raw
ethernet, so I would like to better explain my project. At this moment I'm
trying to study raw ethernet performances in a sort of dummy way that
means that I made two programs, the first one to send raw packets and the
second one to receive them and make statistics (received frames, lost
frames, time spent, throughput and so on).
My purpose is to study raw ethernet performances and to understand the
problems linked to this approach (raw ethernet). For example, I've seen
that raw ethernet is unreliable so I loose packets (even if my two nodes
are connected by a point-to-point gigabit link). I'm interested in
understand why I have a packet loss (interrupt management, full rx ring,
rx buffer overflow, each of them combined?) Now I'm trying to modulate the
problem with instruments such as ifconfig, or other infos captured by some
kernel's constants (i.e. /proc/net/softnet_stat), but I'm searching tools
which can give me more precision and accurate results. In your opinion
what can I use? In alternative I can see the driver source to understand
how and where it allocates rxdescriptors, or sk_bufs to storage incoming
packets even if it seems a long work.

Simone Saravalli

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