When running single-core, some drivers tend to call rte_delay_us for a
long time, and that is causing packet drops.
To avoid this, rte_delay_us can be replaced with user-defined delay
function with:
void rte_delay_us_callback_register(void(*userfunc)(unsigned));
When userfunc==rte_delay_us_block build-in blocking delay function is
restored.
Signed-off-by: Jozef Martiniak <jozmarti@cisco.com>
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