[srslte-users] Replace some PHY pre-calculations with fast on-the-fly routines

[Xavier Arteaga]

Hi John,
Good question! I am delighted to answer that!

The short answer is that you do not need to have a more powerful CPU.

The pre-calculated sequences took too much memory and it was likely to have
cache misses.

Single thread benchmark `phy_dl_test` may show lower throughput than it
used to. In contrast, the on-the-fly routines show better computing
performance when the system is loaded.

My answer is based on:
- `$ lib/test/phy/phy_dl_test -p 100 -m 27 -q -t 1 -s 10000` using an i7
7800X at fixed 4.5GHz;
- synthetic workload with `stress -m 2`;
- Release 20.10 vs 21.04 performance are similar without load;
- Release 21.04 performance is greater under load.

- Release 20.10 phy_dl_test benchmark:
[Rates in Mbps] Granted  Processed
           eNb:    97.9      411.2
            UE:    97.9      267.7

- Release 20.10 phy_dl_test benchmark simultaneous with `stress -m 2`:
[Rates in Mbps] Granted  Processed
           eNb:    97.9      376.4
            UE:    97.9      246.9

- Release 21.04 phy_dl_test benchmark:
[Rates in Mbps] Granted  Processed
           eNb:    97.9      401.4
            UE:    97.9      268.3

- Release 21.04 phy_dl_test benchmark simultaneous with `stress -m 2`:
[Rates in Mbps] Granted  Processed
           eNb:    97.9      379.9
            UE:    97.9      256.7

Regards,
Xavier

On Wed, 12 May 2021 at 11:13, John Wu <john3851 at 126.com> wrote:

> Hi,
> in 20.10 release note i saw Replace some PHY pre-calculations with fast
> on-the-fly routines. does this mean this version will need more powerful
> cpu than previous release?
>
>
>
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