One can call vlib_trace_buffer(...) anywhere, but doing so on a packet which is already traced - from one of the input nodes - has a peculiar "fork" effect which may prove confusing.
As Chris wrote: [we hope that] all device input nodes are capable of calling vlib_trace_buffer. Few if any interior nodes call it, so "trace add <input-node-name> <count>" is the usual strategy... FWIW... Dave -----Original Message----- From: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> On Behalf Of Christian Hopps Sent: Friday, September 20, 2019 6:59 AM To: wei_sky2...@163.com Cc: Christian Hopps <cho...@chopps.org>; vpp-dev@lists.fd.io Subject: Re: [vpp-dev] About VPP trace，why I trace add ip4_lookup, but when i show ,it does't have any record? Only input nodes are capable of starting a trace on a packet. Thanks, Chris. > On Sep 20, 2019, at 4:55 AM, wei_sky2...@163.com wrote: > > I use commond "trace add ip4_lookup 10" in vppctl. > when I show trace,no packets is recorded, why? > And I use trace add dpdk_input 10 , some packets can be recorded. > Thanks! -=-=-=-=-=-=-=-=-=-=-=- > Links: You receive all messages sent to this group. > > View/Reply Online (#14028): https://lists.fd.io/g/vpp-dev/message/14028 > Mute This Topic: https://lists.fd.io/mt/34228502/1826170 > Group Owner: vpp-dev+ow...@lists.fd.io > Unsubscribe: https://lists.fd.io/g/vpp-dev/unsub [cho...@chopps.org] > -=-=-=-=-=-=-=-=-=-=-=-
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