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... i noticed in setup time, slack is -6.048. and end point tns is -11072.420. (why this value is so high) i dont know.
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Think of TNS (total negative slack) as being the sum of the negative slack of all the failing paths. It's not really that simple, but that gives you an idea of what it means.
I don't remember how the actual calculation was explained to me. A single source register going to a single destination register might have multiple paths between these two registers, and there might be more than one of these paths failing. TNS might be the sum of the negative slack for just the worst failing path of each source/destination register pair and not include the slack for the other failing paths for register pairs that have more than one path between them.
TNS gives you a metric for judging how bad the overall timing performance is. If slack is -6.048 ns and TNS is also -6.048 ns, you know you have only one failing path (or, based on my guess in the previous paragraph, maybe just one failing register pair that might have more than one failing path between those two registers). That might be easy to fix. If slack is merely -0.5 ns and TNS has a huge magnitude, you know you have lots of failing paths that need to be fixed. For your combination of -6.048 ns slack and -11072.420 ns TNS, you know without even running report_timing on this clock domain that you have many failing paths using this clock.
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