The role of the VLIB_BUFFER_TRACE_ transaction macro
You can record the number of node passed by mbuf and the index of node passed by mbuf in mbuf by enabling macro index:
If (VLIB_BUFFER_TRACE_TRAJECTORY & & frame)
{
Int i
Int log_index
U32 * from
From = vlib_frame_vector_args (frame)
For (I = 0; I)
< frame->Nasty vectors; iSuppli +)
{
Vlib_buffer_t * b = vlib_get_buffer (vm, from [I])
ASSERT (b-> pre_data [0])
< 32); log_index = b->Pre_data [0] + 1
B-> pre_ data [log _ index] = node- > node_index
}
N = node- > function (vm, node, frame)
}
Print the recorded node information with the following function
Void vlib_dump_context_trace (vlib_main_t*vm, U32 bi)
{
Vlib_node_main_t * vnm = & vm- > node_main
Vlib_buffer_t * b
U8 i, n
If (VLIB_BUFFER_TRACE_TRAJECTORY)
{
B = vlib_get_buffer (vm, bi)
N = b-> pre_data [0]
Fformat (stderr, "Context trace for bi% d b 0x%llx, visited%d\ n"
Bi, b, n)
If (n = = 0 | | n > 20)
{
Fformat (stderr, "n is unreasonable\ n")
Return
}
For (I = 0; I)
< n; i++) { u32 node_index; node_index = b->Pre_ data [I + 1]
If (node_index > vec_len (vnm- > nodes))
{
Fformat (stderr, "Skip bogusnode index% d\ n", node_index)
Continue
}
Fformat (stderr, "% v (% d)\ n", vnm- > Nodes [node _ index]-> name
Node_index)
}
}
Else
{
Fformat (stderr
"in vlib/buffers.h,#define VLIB_BUFFER_TRACE_TRAJECTORY 1\ n")
}
}
