On 27/05/15 19:50, Mike Holmes wrote:
On 27 May 2015 at 14:45, Ola Liljedahl <[email protected]
<mailto:[email protected]>> wrote:
On 27 May 2015 at 19:30, Zoltan Kiss <[email protected]
<mailto:[email protected]>> wrote:
Hi,
While hunting some ODP-DPDK bugs I've found something which
needs clarification: what happens with those packets not sent by
odp_pktio_send()? This is the case when e.g. there is no free TX
descriptors, so the function returns with less than "len". Our
examples either doesn't seem to do anything about that, or
handle it as a failure. But a real world application should be
able to handle that. I can see two options:
- odp_pktio_send() calls odp_packet_free on the packets which
were not successfully sent.
In this case, odp_pktio_send() could also return "len". All packets
were taken care of (one way or the other). Transmission is not
guaranteed, packets can go missing practically anywhere.
Pro: we can have better information about which buffers exactly
were not sent (although rationally, the last "len-<retval>"
packets). Cons: the application might have other plans with
those packets, e.g. send them later
- The application has to handle those packets. Pro: more choice,
not just dropping. Cons: we have to mandate that the last
"len-<retval>" packets have to be the ones which were not sent.
If an implementation fails to send (transmit, enqueue, whatever)
packet N, it should stop trying to send any more packets in the
vector and just return N. So 0..N-1 were sent and N..len-1 were not
sent.
I can't come up with a scenario where it wouldn't be the case
anyway, but I have a gut feeling it can happen, and platforms
have to handle that
I prefer the second option, that's how DPDK handles that too. It
needs a comment upgrade in the API, and fixing our usage of
odp_pktio_send around the code base to release the not sent packets.
Agree.
Can you describe what is needed in a Bug Zoltan ?
https://bugs.linaro.org/enter_bug.cgi?product=OpenDataPlane
I've sent in a patch instead: "[PATCH] api-next: packet_io: clarify what
happens when not all packets are sent"
Zoli
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--
Mike Holmes
Technical Manager - Linaro Networking Group
Linaro.org <http://www.linaro.org/>***│ *Open source software for ARM SoCs
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