| Info | HW section | SW section | Addr space | Interface | Versions |
| Authors: | Tomas Pecenka |
| Martin Zadnik |
Statistic Unit (STU) allows to create length and time statistic (number of packects, average packet length, minimal and maximal packet length, average interpacket time, etc.). Statistic unit contains 256 virtual statistic cores implemented as 256 sets of registers and only one processing unit. Set of registers which is used for statistic for actual packet is determined by LUP record.
Subcomponents:
Statistic of packet length (STU_LENGTH) performs several tasks: counts number of packets, sum of lengths of packets, sum of squares of packets lengths and store min/max length of packet. STU_LENGTH uses an address vector created by LUP and length of packet (provided by HFE) as inputs. According to address vector (8bit), statistic values are loaded from registers, processed with packet length and new statistic values are stored back. All statistic information are provided to software layer via localbus. Once they are read, they are zeroized and new gathering of statistic data begins.
Component for statistic of inter-packet interval (STU_TIME) performs several tasks: counts number of packets, sum of intervals between packets, sum of squares of intervals and store min/max interval between two contiguous packets. STU_TIME uses an address vector created by LUP and actual timestamp (provided by TSU) as inputs. According to address vector (8bit), statistic values are loaded from registers, processed with inter-packet interval and new statistic values are stored back. All statistic information are provided to software layer via localbus. Once they are read, they are zeroized and new gathering of statistic data begins.
Statistic blocks
The Statistic unit has two parts:
- packets lengths statistics,
- statistics of intervals between packets.
STU perform following tasks:
- count number of packets,
- store sum of lengths of packets,
- store sum of squares of packets lengths,
- store min/max of packet length,
- set overflow flags,
- store sum of inter-packet intervals,
- store sum of square of inter-packet intervals,
- store min/max of inter-packet interval,
- store timestamp of last packet,
- set overflow flags (the same like in 'length' part).
STU inputs are: address vector created by LUP, packet-length vector provided by HFE and Timestamp from TSU. According to address vector statistic values in various BlockRams are picked. Than processed with packet length and timestamp values and new statistic values are stored in belonging Blockrams. Statistic unit stores all statistic information and provides them to software layer via localbus. Once they are read new gathering of statistic data begins (each register is set to zero after read).
