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I performed a test in which I transferred a file of 1GB by opening a tcp port on destination server with MTU 1000.

then I tried to change the MTU from 1000 to 9000 and the total time duration of 1GB file transfer from source to destination server was same. I tried the same process of 5GB file size and difference in time was negligible. Not sure if this could be different for bigger file size(100GB)

I can confirm that max MTU is supported from both of my server(source and destination support MTU 9001)

Any suggestion please.

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As discussed in this question, using Ethernet jumbo frames to raise the MTU from 1500 to 9000 bytes may increase efficiency and usable throughput by 4.4% (line efficiency rises from 94.93% to 99.14%), so a significant increase cannot be expected.

In reverse, lowering the maximum frame size to an MTU of 1000 decreases line efficiency to 92.13%, lowering possible throughput by 2.95% - also not really significant.

Jumbo frames were intended to lower the processing overhead by lowering the packet rate to increase the throughput beyond the pure line efficiency/encoding overhead improvement. However, modern NICs usually feature offloading capabilities, lowering the processing overhead to a similar amount (thx Marc!). Therefore, you can't expect to see significant changes except for fringe cases.

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    Plus, contemporary hardware (NICs) and network stacks have the capability to offload compute intensive tasks to the NIC, for example checksum calculations. This offers just as much efficiency benefits as jumbo frames once promise(d) with their lower (expected) overhead.
    – Marc 'netztier' Luethi
    Commented Nov 24, 2023 at 8:38

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