From: Prashant Batra <prbatra.lists@gmail.com>
To: linux-newbie@vger.kernel.org
Subject: Route lookup in ip_finish_output2
Date: Mon, 11 Feb 2013 14:24:59 +0530 [thread overview]
Message-ID: <5118B1E3.1040409@gmail.com> (raw)
Hi Folks,
I am trying to do a small hack into the kernel just for some
experimentation wherein I need to do a ipv4 route lookup from
ip_finish_output2, after the packet is received from outside and has got
forwarded.
The route lookup is done using kernel API "ip_route_output_flow" with
the flow having the dst address.
This seems to be working fine with only exception that at very high
loads, I see certain CPU hikes and the profiling results show that the
same API comes out to be the culprit.
What I understand is that even to take the forwarding decision the
kernel ip_rcv should have done the route lookup to decide that the
packet needs to be forwarded, then why am I seeing a CPU hike in my case.
The second route lookup is done as the original packet has got
encapsulated within a new IP header having a different destination than
the original packet.
Thanks,
Prashant
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reply other threads:[~2013-02-11 8:54 UTC|newest]
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