Lookahead legalization based global placement for heterogeneous FPGAs

2017 ◽  
Author(s):  
Sharbani Purkayastha ◽  
Shyamapada Mukherjee
Keyword(s):  
Global Placement

scholarly journals A Sea-of-Gates Style FPGA Placement Algorithm

VLSI Design ◽  
1996 ◽  
Vol 4 (4) ◽  
pp. 293-307
Author(s):  
Kalapi Roy ◽  
Bingzhong (David) Guan ◽  
Carl Sechen
Keyword(s):  
Chip Area ◽  
Field Programmable ◽  
Fpga Placement ◽  
Programmable Gate Arrays ◽  
Placement Algorithm ◽  
Two Phases ◽  
Fixed Cell ◽  
Flexible Architectures ◽  
Design Style ◽  
Global Placement

Field Programmable Gate Arrays (FPGAs) have a pre-defined chip boundary with fixed cell locations and routing resources. Placement objectives for flexible architectures (e.g., the standard cell design style) such as minimization of chip area do not reflect the primary placement goals for FPGAs. For FPGAs, the layout tools must seek 100% routability within the architectural constraints. Routability and congestion estimates must be made directly based on the demand and availability of routing resources for detailed routing of the particular FPGA. We. present a hierarchical placement approach consisting of two phases: a global placement phase followed by a detailed placement phase. The global placement phase minimizes congestion estimates of the global routing regions and satisfies all constraints at a coarser level. The detailed placer seeks to maximize the routability of the FPGA by considering factors which cause congestion at the detailed routing level and to precisely satisfy all of the constraints. Despite having limited knowledge about the gate level architectural details, we have achieved a 90%reduction in the number of unrouted nets in comparison to an industrial tool (the only other tool) developed specifically for this architecture.

scholarly journals The dynamics of faculty hiring networks

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Eun Lee ◽  
Aaron Clauset ◽  
Daniel B. Larremore
Keyword(s):  
Network Models ◽  
Structural Mechanism ◽  
Faculty Hiring ◽  
Network Characteristics ◽  
Institutional Prestige ◽  
Structural Mechanisms ◽  
Global And Local ◽  
Global Placement ◽  
New Hire

AbstractFaculty hiring networks—who hires whose graduates as faculty—exhibit steep hierarchies, which can reinforce both social and epistemic inequalities in academia. Understanding the mechanisms driving these patterns would inform efforts to diversify the academy and shed new light on the role of hiring in shaping which scientific discoveries are made. Here, we investigate the degree to which structural mechanisms can explain hierarchy and other network characteristics observed in empirical faculty hiring networks. We study a family of adaptive rewiring network models, which reinforce institutional prestige within the hierarchy in five distinct ways. Each mechanism determines the probability that a new hire comes from a particular institution according to that institution’s prestige score, which is inferred from the hiring network’s existing structure. We find that structural inequalities and centrality patterns in real hiring networks are best reproduced by a mechanism of global placement power, in which a new hire is drawn from a particular institution in proportion to the number of previously drawn hires anywhere. On the other hand, network measures of biased visibility are better recapitulated by a mechanism of local placement power, in which a new hire is drawn from a particular institution in proportion to the number of its previous hires already present at the hiring institution. These contrasting results suggest that the underlying structural mechanism reinforcing hierarchies in faculty hiring networks is a mixture of global and local preference for institutional prestige. Under these dynamics, we show that each institution’s position in the hierarchy is remarkably stable, due to a dynamic competition that overwhelmingly favors more prestigious institutions. These results highlight the reinforcing effects of a prestige-based faculty hiring system, and the importance of understanding its ramifications on diversity and innovation in academia.

Logical Core Algorithm: Improving Global Placement

2010 ◽  
Author(s):  
Felipe Pinto ◽  
Lucas Cavalheiro ◽  
Marcelo Johann ◽  
Ricardo Reis
Keyword(s):  
Global Placement

An Effective Cell Spreading Method for Force-Directed Global Placement

2014 ◽  
Vol 519-520 ◽  
pp. 911-918
Author(s):  
Xin Min Ma ◽  
Xu Qian ◽  
Wen Chao Gao
Keyword(s):  
Large Scale ◽  
Decisive Role ◽  
Cell Spreading ◽  
Fast Method ◽  
Wire Length ◽  
Additional Force ◽  
Large Scale Integration ◽  
Initial Placement ◽  
Scale Integration ◽  
Global Placement

Force-directed placement method for large scale integration physical design is a very effective and fast method to spread the cell uniformly in the placement region. But this kind of method also create large amount of cell overlap in initial placement. In this paper, we present an effective method to cope with cell spreading and add additional force without damaging the wire length. It mainly takes the following method: Firstly, in the prior period of iteration n we keep limit the cell moving distance using a rectangle structure .Because the prior iteration play a decisive role in the final placement quality. Secondly, after the cell relative order determined we can use a new method to compute the weight of additional force to accelerate converge. Thirdly, a strategy called iterative local refinement is added in the well-distributed placement to further reduce the total wire length.

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