Update benchmarker and buildbot dockers

[mattip]

It turns out the benchmarker machine that drives speed.pypy.org was set up in 2016. It is running benchmarks in a xenial (ubuntu 16.04) sandbox, using the gcc 5.3.1 that was part of the xenial then. It may be time to retire this "machine" and update the sandbox to resolute (26.04). We should probably update the buildbot docker images as well to manylinux_2_28 from manylinux2014

[mattip]

Putting this here as a plan for setting up a new benchmarking machine that would be newer and more stable than benchmarker. The idea would be to split off some of the cores and use them exclusively for benchmarking, while allowing buildbot master and the 32bit builds (with a lock to not run while benchmarking runs) to run on the machine as well.

Basic layout for an AMD Ryzen 5 3600 with 6 cores

Host OS: Ubuntu 24.04 LTS: a recent kernel with amd_pstate support.

Kernel boot parameters (in /etc/default/grub):

nosmt — disable SMT
isolcpus=0-2 nohz_full=0-2 rcu_nocbs=0-2 — isolate one CCX (adjust core IDs after verifying CCX layout with lscpu --extended or lstopo)
irqaffinity=3-5 - pin IRQs to the non-benchmark CCX
processor.max_cstate=1 - cap C-states (or idle=pollfor maximum aggression)amd_pstate=passive- modern AMD pstate driver under cpufreq controltransparent_hugepage=never mitigations=...` make a deliberate choice (off = max consistency, on = realistic), document it

Post-boot tweaks (systemd unit, runs on boot):

cpufreq governor -> performance on all CPUs
Disable Core Performance Boost: echo 0 > /sys/devices/system/cpu/cpufreq/boost
Pin frequency: scaling_min_freq = scaling_max_freq = 3600000 (base clock)
swap off (or at least off on the benchmark cgroup)
Assert all of the above on every boot; failing loudly if anything is off

CPU isolation: Ryzen 5 3600 has two CCXs of 3 cores with 16 MB L3 each, not shared between CCXs. Pin all benchmark processes to one CCX, everything else (host, buildbot master, 32-bit worker) to the other. After nosmt you have 6 usable cores → 3 + 3. This gives genuinely separate L3 caches for the two workloads. Memory bandwidth and Infinity Fabric are still shared but unavoidable on this chip.
Chroot OS: Debian 13 (Trixie), stock GCC 14.2. Solves the GCC 5 computed-goto codegen problem fully; five years of stable support; minimal toolchain churn over the environment's life. Same image for the 32-bit buildbot worker container, using multilib for 32-bit builds.
Treat this as a new speed.pypy.org environment; document the full configuration (kernel cmdline, sysfs assertions, chroot definition) alongside it so the setup is reproducible and any drift is detectable.