Proposed platform is composed of a working symmetric multi-processor systems (SMP) based on four LEON3 cores, enhanced by adding a custom hardware profiling system with no software overhead introduction. A SMP LINUX kernel targeting the proposed system and including the device drivers needed to collect data from the custom hardware profilers has been also built. The system has been further customized to support the execution of OpenMP-based applications.

1. LINUX
+
OPENMP
LEON3
LEON3
LEON3
LEON3
S 1
S 2
S 3
AHB
Controller
LEON3 LEON3 JTAG
Dbg Link
Ethernet
MAC
LEON3 LEON3 AHB/APB
Bridge
Memory
Controller
JTAG PHY
AMBA AHB
AMBA APB
UARTUART - USB SRAM
S1 S2 S3
Non-parallel region:
Master thread only
Parallel region starts:
#pragma omp parallel
ID:0
fork
ID:0 ID:1 ID:2 ID:3
Parallel region:
Several thread execute
simultaneously
join
Parallel region ends:
program waits for all
threads to terminate
ID:0
Program reverts to single
threaded execution
APB
Interface
Decode
Section
Event
Monitor
Time
Monitor
Counter
AHB - Adapter
APB
Bus
AHB Bus
SNIFFER BLOCK DIAGRAM
LEON3
7 - Stage
Integer Pipeline
3-Port Register File
IEEE-754 FPU
Co-Processor
HW MUL/DIV
Trace Buffer
Debug port
Interrupt port
I-Cache D-Cache
SRMMU
AHB I/F
Local IRAM
ITLB
Local DRAM
DTLB
AMBA AHB Master (32-bit)
SYSTEM BEHAVIOUR
Perfomance evaluation
of the platform by
means of Pi calculation
algorithm, proposed in
four different versions:
serial computation,
single process multiple
data (SPMD) technique
with false sharing,
SPMD technique
without false sharing
and OMP reduction
function.
Proposed profiling technique, used to monitor computational behaviour of the 4-LOOP platform, follows the
approach of runtime bus sampling.
LEGEND:
1 Thread
2 Threads
3 Threads
4 Threads
Event monitor:
strobe generation
(ld_ac_event) during
access on specified
address range
(delimited by
sig_out_inf and
sig_out_sup).
Time monitor:
counter activated by
read operation
(during_read) and
stopped by write
operation
(during_write), both
on specified address
(0x808).
LEON3 HW PROFILING SYSTEM
SYSTEM DESCRIPTION
The LEON3 processor is designed for Embedded applications,
combining high performance with low complexity and low power
consumption. The LEON3 processor is highly configurable.
A distributed hardware profiling system has been developed for runtime analysis.
It is composed of distributed AHB bus monitoring elements (sniffers) that moni-
tor AHB bus, initialized by means of APB bus. A global monitor unit, represented
by one LEON3 processor, provides sniffers initialization and collects results.
A Linux distribution, customized to work with multicore platform
in SMP mode, has been developed using Buildroot tool, starting
from LEON LINUX kernel (provided by Gaisler research).
Libraries required to implement parallel applications using shared memory,
developed with OpenMP C/C++, have been cross-compiled and added to the
adopted Linux distribution.
LINUX OPENMP
HARDWARE ARCHITECTURE
THE PLATFORM
OVERVIEW
The opportunity to build multi-processor systems exploiting soft-cores is increasing the
range of applications that can be implemented on FPGAs.
Inordertomaximizeperformanceaparallelprogrammingmodelshouldbeused:OpenMPAPI
is a specification for a set of compiler directives, library routines, and environment variables
that can be used to specify high-level parallelism.
Runtime analysis on SoC is useful to optimize reconfigurable systems. However, software
profiling systems impose software overhead to application execution.
1)
2)
3)
Proposed platform is composed of a working symmetric multi-processor
systems (SMP) based on four LEON3 cores, enhanced by adding a custom hardware
profiling system with no software overhead introduction. A SMP LINUX kernel
targeting the proposed system and including the device drivers needed to collect data
from the custom hardware profilers has been also built. The system has
been further customized to support the execution of OpenMP-based applications.
PROPOSED PLATFORMMOTIVATIONS
4-LOOP IS A PLATFORM DEVELOPED TO OFFER ADVANTAGE OF PARALLEL EXECUTION, WHILE MONITORING RUNTIME SYSTEM
BEHAVIOUR WITHOUT SOFTWARE OVERHEAD
4 - LOOP LEON34-CORE LEON3 WITH LINUX OPERATING SYSTEM, OPENMP LIBRARY AND HARDWARE PROFILING SYSTEM
G. Valente, V. Muttillo, L. Pomante, M. Faccio, F. Federici, A. Moro
Main Contacts: giacomo.valente@graduate.univaq.it, luigi.pomante@univaq.it, marco.faccio@univaq.it, fabio.federici@univaq.it
UNIVERSITA’ degli STUDI dell’AQUILA - CENTER of EXCELLENCE DEWS (ITALY)
http://dews.univaq.it
Graphic Designed By: Tania Valentina Ferro