Could anybody show me, where I can make sure how to convert a transfer rate to the clock rate for UPI? Or where to see exactly numbers from Intel docs.
For example, for QPI, the Wiki says:
"Intel describes the data throughput (in GB/s) by counting only the 64-bit data payload in each 80-bit flit. However, Intel then doubles the result because the unidirectional send and receive link pair can be simultaneously active. Thus, Intel describes a 20-lane QPI link pair (send and receive) with a 3.2 GHz clock as having a data rate of 25.6 GB/s. A clock rate of 2.4 GHz yields a data rate of 19.2 GB/s. More generally, by this definition a two-link 20-lane QPI transfers eight bytes per clock cycle, four in each direction.
The rate is computed as follows:
- 3.2 GHz
- × 2 bits/Hz (double data rate)
- × 16(20) (data bits/QPI link width)
- × 2 (unidirectional send and receive operating simultaneously)
- ÷ 8 (bits/byte)
- = 25.6 GB/s"
For UPI transfer rate is 10.4 GT/s.
How to get the corresponding physical frequency in one separate diff. pair?
Need to clarified:
The Wiki says about bit rate (GB/s), but for UPI specified the transfer rate (GT/s).
Is this means that we only need to take into account:
unidirectional send and receive operating simultaneously,
the doubling because of reading in fall and rise of clock signal (if it is present)
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