Boosting performance with network tuning

The network represents one of the most complex and key elements involved in tuning the system. Being an externally self-organizing element, some network elements could affect performance. To identify and adjust them, it is necessary to know the flow that a packet follows both when transmitted and received by a system, as well as the tuning options available for them.

The transmission and reception flow of the packet is roughly as follows:

• Transmission:
  1. Data gets written to a socket (an object such as a file) and sent to the transmit buffer.
  2. The kernel encapsulates the data in a protocol data unit (PDU).
  3. The PDUs go to the device’s transmit queue.
  4. The network device driver copies the PDU from the transmit queue header to the NIC.
  5. The NIC sends the data and triggers an interrupt when transmitted.
• Reception:
  1. The NIC receives a frame and uses DMA to copy the frame to the receive buffer.
  2. The NIC triggers a hard interrupt.
  3. The kernel...