[Pkg-raspi-maintainers] Bug#1007719: raspi-firmware: Performance regression under RPi4B

[Gunnar Wolf]

Package: raspi-firmware
Version: 1.20220120+ds-1
Severity: important
Tags: upstream

Hank Barta reported a performance regression under the Raspberry Pi
4B, after comparing Bullseye and Bookworm (Debian 11 and 12). I am
copying over to this bug report only part of the information; a
full(er) report is available in Hank's GitHub project
Pi-4B-bookworm-performance:

    https://github.com/HankB/Pi-4B-bookworm-performance

The problem presented when running sysbench:

   /--- bullseye ↓
   | $ time sysbench --test=cpu --cpu-max-prime=20000 run
   | (...)
   | CPU speed:
   |     events per second:   584.72
   |
   | General statistics:
   |     total time:                          10.0006s
   |     total number of events:              5850
   | Latency (ms):
   |       min:                                    1.70
   |       avg:                                    1.71
   |       max:                                    2.99
   |       95th percentile:                        1.73
   |       sum:                                 9997.34
   |
   | Threads fairness:
   |     events (avg/stddev):           5850.0000/0.00
   |     execution time (avg/stddev):   9.9973/0.00
   +--- bookworm ↓
   | # time sysbench --test=cpu --cpu-max-prime=20000 run
   | (...)
   | CPU speed:
   |  events per second:   233.03
   | 
   | General statistics:
   |     total time:                          10.0038s
   |     total number of events:              2333
   | 
   | Latency (ms):
   |          min:                                    4.28
   |          avg:                                    4.29
   |          max:                                    4.34
   |          95th percentile:                        4.33
   |          sum:                                10001.67
   | 
   | Threads fairness:
   |     events (avg/stddev):           2333.0000/0.00
   |     execution time (avg/stddev):   10.0017/0.00
   \---

Hank did a thorough saerch, and found out this issue happens after the
firmware update (raspi-firmware/testing 1.20220120+ds-1 arm64
[upgradable from: 1.20210805+ds-1]).

Further information is available on the debian-arm mailing list
thread:

    https://lists.debian.org/debian-arm/2022/03/threads.html#00003

I prompted Hank to report this issue to the Raspberrrypi Firmware
project in GitHub, which he did, but was outright dismissed:

    https://github.com/raspberrypi/firmware/issues/1705

-- System Information:
Debian Release: bookworm/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 5.16.0-3-amd64 (SMP w/8 CPU threads; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

-- 

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