Agree with Ola. Completed TX ring resources can be freed in the next odp_pktio_send/odp_pktio_recv/odp_schedule/etc calls. Application should not care how and when those resources are freed. It would be awkward if implementation requires application to call the flush function e.g. every 1ms, or otherwise some send calls may start failing, etc.
-Petri From: lng-odp [mailto:lng-odp-boun...@lists.linaro.org] On Behalf Of ext Ola Liljedahl Sent: Thursday, May 28, 2015 7:41 PM To: Zoltan Kiss Cc: LNG ODP Mailman List Subject: Re: [lng-odp] [API-NEXT PATCH] api-next: pktio: add odp_pktio_send_complete() definition On 28 May 2015 at 17:23, Zoltan Kiss <zoltan.k...@linaro.org<mailto:zoltan.k...@linaro.org>> wrote: On 28/05/15 16:00, Ola Liljedahl wrote: I disprove of this solution. TX completion processing (cleaning TX descriptor rings after transmission complete) is an implementation (hardware) aspect and should be hidden from the application. Unfortunately you can't, if you want your pktio application work with poll mode drivers. In that case TX completion interrupt (can be) disabled and the application has to control that as well. In case of DPDK you just call the send function (with 0 packets, if you don't have anything to send at the time) Why do you have to retire transmitted packet if you are not transmitting new packets (and need those descriptors in the TX ring)? Does the application have too few packets in the pool so that reception will suffer? There isn't any corresponding call that refills the RX descriptor rings with fresh buffers. You can do that in the receive function, I think that's how the drivers are doing it generally. The completion processing can be performed from any ODP call, not necessary odp_pktio_send(). I think "any" is not specific enough. Which one? odp_pktio_recv, odp_schedule. Wherever the application blocks or busy waits waiting for more packets. Can you provide a vague draft how would you fix the l2fwd example below? I don't think anything needs fixing on the application level. -- Ola On 28 May 2015 at 16:38, Zoltan Kiss <zoltan.k...@linaro.org<mailto:zoltan.k...@linaro.org> <mailto:zoltan.k...@linaro.org<mailto:zoltan.k...@linaro.org>>> wrote: A pktio interface can be used with poll mode drivers, where TX completion often has to be done manually. This turned up as a problem with ODP-DPDK and odp_l2fwd: while (!exit_threads) { pkts = odp_pktio_recv(pktio_src,...); if (pkts <= 0) continue; ... if (pkts_ok > 0) odp_pktio_send(pktio_dst, pkt_tbl, pkts_ok); ... } In this example we never call odp_pktio_send() on pktio_dst if there wasn't any new packets received on pktio_src. DPDK needs manual TX completion. The above example should have an odp_pktio_send_completion(pktio_dst) right at the beginning of the loop. Signed-off-by: Zoltan Kiss <zoltan.k...@linaro.org<mailto:zoltan.k...@linaro.org> <mailto:zoltan.k...@linaro.org<mailto:zoltan.k...@linaro.org>>> --- include/odp/api/packet_io.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/include/odp/api/packet_io.h b/include/odp/api/packet_io.h index b97b2b8..3a4054c 100644 --- a/include/odp/api/packet_io.h +++ b/include/odp/api/packet_io.h @@ -119,6 +119,22 @@ int odp_pktio_recv(odp_pktio_t pktio, odp_packet_t pkt_table[], int len); int odp_pktio_send(odp_pktio_t pktio, odp_packet_t pkt_table[], int len); /** + * Release sent packets + * + * This function should be called after sending on a pktio. If the platform + * doesn't implement send completion in other ways, this function should call + * odp_packet_free() on packets where transmission is already completed. It can + * be a no-op if the platform guarantees that the packets will be released upon + * completion, but the application must call it periodically after send to make + * sure packets are released. + * + * @param pktio ODP packet IO handle + * + * @retval <0 on failure + */ +int odp_pktio_send_complete(odp_pktio_t pktio); + +/** * Set the default input queue to be associated with a pktio handle * * @param pktio ODP packet IO handle -- 1.9.1 _______________________________________________ lng-odp mailing list lng-odp@lists.linaro.org<mailto:lng-odp@lists.linaro.org> <mailto:lng-odp@lists.linaro.org<mailto:lng-odp@lists.linaro.org>> https://lists.linaro.org/mailman/listinfo/lng-odp
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