tcpdump mailing list archives

Re: [PATCH] net: Take GSO into account when capturing packets


From: David Miller <davem () davemloft net>
Date: Mon, 06 Jul 2009 18:15:31 -0700 (PDT)

From: Benjamin Poirier <benjamin.poirier () polymtl ca>
Date: Mon, 06 Jul 2009 14:04:32 -0400

move the point where the support routine for packet capture is called to
better reflect what is transmitted on the wire when GSO is active.

At the moment, packet capture (a la tcpdump) on the transmission side happens
before GSO takes place (if it does). Therefore, even if a packet gets
segmented by GSO, the capture shows that one big packet was sent when in fact
many small packets were sent on the wire. This behavior does not reflect the
"reality" of what is transmitted and could lead to confusion, especially since
a capture on the receiving side shows the segmented packets.

Signed-off-by: Benjamin Poirier <benjamin.poirier () polymtl ca>

TSO does the same exact thing except that the networking card
chops up the packet before it hits the wire.

I really doubt there is anything seriously to gain by having
GSO behave one way and TSO another, and we should just keep
things as they are right now.

I'm not applying this, sorry.
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