• Worst Hold Slack
• Negative Slack In Project Management
• Negative Slack Ms Project
• Negative Slack Can Be Created By
• Negative Slack Define

One of the questions that FPGA designers wonder and sometimes even argue about, is: Should the implementation tools focus on Worst Slack (WS) or Total Negative Slack (TNS)?

FPGA tools typically devote more attention to WS, but there are tradeoffs. If WS is small yet many paths fail timing, then TNS can be huge. Similarly, if TNS is slight but WS is failing by a lot, that is also a problem.

To answer this question, we added a feature to collate the data for both timing values and ran about 1000 compilations on a small design (Cyclone V, about 9% utilization) using different synthesis and fitter settings.

• There are actually two probably causes of negative Total Slack: The schedule has slipped past an inflexible constraint (such as a Must Finish On constraint). The schedule has slipped past a Deadline date. Since you say you have no constraints in the project, do you have any Deadline dates?
• Negative Total Slack is caused by a task's Finish date slipping past its Deadline date or a hard constraint date (such as a Finish No Later Than constraint). So, in your case, I would say the missed Deadline date is the cause.

Slack is a new way to communicate with your team. It’s faster, better organized, and more secure than email. Slack is defined as difference between actual or achieved time and the desired time for a timing path. Negative setup slack implies that design doesn’t achieve.

This is what we see. The default result is marked by the black dot. The Y-axis represents the absolute value of the TNS and the X-axis, the absolute value of failing WS.

The chart is divided into 4 quadrants, green means these compilations give better TNS and WS compared to the original design.

Worst Hold Slack

Besides looking like a pretty smattering of colored dots, we can see that the TNS flattens out when it is closer to zero but the worst slack still keeps improving.

Negative Slack In Project Management

Negative Slack Ms Project

Taking a closer look,

Negative Slack Can Be Created By

What do you think?
Make your own conclusions, and please share your thoughts with us!

Negative Slack Define

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