From: "Sridhar.V.Iyer" <sridhariyer@versa-networks.com>
To: dev@dpdk.org
Subject: [dpdk-dev] Packet drops at lower tc transmit-rates.
Date: Thu, 7 Apr 2016 12:24:04 -0700 [thread overview]
Message-ID: <C5AB8E4F-C3EB-468D-83FA-56E5B38B3ED6@versa-networks.com> (raw)
Hi all,
We are using DPDK 1.7 in our application.
We are running into an issue where a lower transmit-rate configured at the traffic class of a subport is causing complete packet drops.
Here are few parameters to clear up some context:
Packet length = 728 byte
Port rate = 1Gbps = 12500000 bytes/s
Subport tc_period = 10 ms
Configured TC0 rate = 500 kbps = 62500 bytes/s
This means that for the given subport tc0_credits_per_period = 10 * 62500 / 1000 = 625 (from rte_sched_subport_config)
Now, there is no token bucket at the subport-tc level, so there are no credits to accrue. The tc0_credits are just initialized to 625.
- This means that we’ll never have “enough_credits” in grinder_credits_check to process a 728 byte packet.
- grinder_schedule will then return 0.
- grinder_handle will return 0.
- which implies that the rte_sched_port_dequeue will never dequeue any packet.
- After port->time exceeds the subport->tc_time, tc0_credit will be re-initialized back to 625 again.
Is this a bug in the logic?
What are some of the viable workarounds?
Is this issue taken care of in the later releases?
Regards,
Sridhar V Iyer
<http://www.versa-networks.com/> <http://www.versa-networks.com/>
next reply other threads:[~2016-04-07 19:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-07 19:24 Sridhar.V.Iyer [this message]
2016-04-11 21:00 ` Dumitrescu, Cristian
2016-04-12 23:38 ` Sridhar.V.Iyer
2016-04-13 9:31 ` Dumitrescu, Cristian
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