1. A system for input data load adaptive processing of a set of software programs sharing a manycore processor, with each of said programs having one or more instances, and with said instances of the programs referred to as program instances, the system comprising: a collection of hardware input data ports of the processor, where each port of the collection is shared dynamically among data packets for the program instances; an array of hardware buffers, where each buffer of the array is specific to an individual destination program instance among said program instances; a logic subsystem for dynamically, at individual packet granularity, demultiplexing input data packets from said input ports to said destination program instance specific buffers based on a destination program instance indication of any given one of the packets by overhead information of the given packet; a logic subsystem for monitoring volumes of data packets at the program instance specific buffers and for periodically assigning processing cores of the processor among individual program instances among said program instances at least in part based on the respective monitored volumes of packets at the program instance specific buffers; and a logic subsystem for multiplexing data packets dynamically from the destination program instance specific buffers to the processor cores so that, to any given one of the processor cores, packets are multiplexed from the buffers that are specific to the program instance that the logic subsystem for assigning has presently assigned to the given processor core, wherein, in case the system is a part of a multi-stage group of two or more of the manycore processors, at a given one of such processors, the logic subsystem monitoring volumes and for periodically assigning the processor cores of the given processor inserts an identification of a destination program for a data packet passed from the given processor to other processors of the group, to provide isolation between different programs among the set.