Publications by Stefan Nikolic

Exploring FPGA Switch-Blocks without Explicitly Listing Connectivity Patterns

Increased lower metal resistance makes physical aspects of Field-Programmable Gate Array (FPGA) switch-blocks more relevant than before. The need to navigate a design space where each individual switch can have significant impact on the FPGA's performance ...

2024

IIBLAST: Speeding Up Commercial FPGA Routing by Decoupling and Mitigating the Intra-CLB Bottleneck

Mirjana Stojilovic, Stefan Nikolic, Shashwat Shrivastava

We identified that in modern commercial FPGAs, routing signals from the general interconnect to the configurable logic blocks (CLBs) through a very sparse input interconnect block (IIB) represents a significant runtime bottleneck. This is despite academic ...

IEEE2023

Regularity Matters: Designing Practical FPGA Switch-Blocks

Paolo Ienne, Stefan Nikolic

Several techniques have been proposed for automatically searching for FPGA switch-blocks which typically show some tangible advantage over the well-known academic architectures. However, the resulting switch-blocks usually exhibit high levels of irregulari ...

Assoc Computing Machinery2023

Automating the Design of Programmable Interconnect for Reconfigurable Architectures

Stefan Nikolic

With Moore's law coming to an end, increasingly more hope is being put in specialized hardware implemented on reconfigurable architectures such as Field-Programmable Gate Arrays (FPGAs). Yet, it is often neglected that these architectures themselves experi ...

EPFL2023

IIBLAST: Speeding Up Commercial FPGA Routing by Decoupling and Mitigating the Intra-CLB Bottleneck

Mirjana Stojilovic, Stefan Nikolic, Shashwat Shrivastava

This repository contains the data and software required to reproduce the results in the paper "IIBLAST: Speeding Up Commercial FPGA Routing by Decoupling and Mitigating the Intra-CLB Bottleneck," by Shashwat Shrivastava (EPFL), Stefan Niko ...

Zenodo2023

Detailed Placement for Dedicated LUT-Level FPGA Interconnect

Paolo Ienne, Grace Zgheib, Stefan Nikolic

In this work, we develop timing-driven CAD support for FPGA architectures with direct connections between LUTs. We do so by proposing an efficient ILP-based detailed placer, which moves a carefully selected subset of LUTs from their original positions, so ...

ASSOC COMPUTING MACHINERY2022

Turning PathFinder Upside -Down: 1-4,xploring FPGA Switch -Blocks by Negotiating Switch Presence

Paolo Ienne, Stefan Nikolic

Automated switch-block exploration gains in importance as technology scaling brings more emphasis on the physical constraints, making it insufficient to rely on abstract measures of routability alone. In this work, we take an approach that significantly di ...

IEEE COMPUTER SOC2021

NetCracker: A Peek into the Routing Architecture of Xilinx 7-Series FPGAs

Mirjana Stojilovic, Stefan Nikolic, Morten Borup Petersen

Novel applications have triggered significant changes at the system level of FPGA architecture design, such as the introduction of embedded VLIW processor arrays and hardened NoCs. However, the routing architecture of the soft logic fabric has largely rema ...

2021

Global Is the New Local: FPGA Architecture at 5nm and Beyond

Paolo Ienne, Stefan Nikolic

2021

Straight to the Point: Intra- and Intercluster LUT Connections to Mitigate the Delay of Programmable Routing

Paolo Ienne, Grace Zgheib, Stefan Nikolic

Technology scaling makes metal delay ever more problematic, but routing between Look-Up Tables (LUTs) still passes through a series of transistors. It seems wise to avoid the corresponding delay whenever possible. Direct connections between LUTs, both with ...

ASSOC COMPUTING MACHINERY2020