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CI: don't pin NIC IRQs to housekeeping CPUs #9568

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Merged
myrrc merged 1 commit into from
Aug 24, 2026
+19 −2
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CI: don't pin NIC IRQs to housekeeping CPUs #9568

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21 changes: 19 additions & 2 deletions scripts/setup-benchmark.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -98,9 +98,26 @@ else
BENCH_CPUS="$(IFS=,; echo "${bench[*]}")"
fi

# Pin all IRQs to housekeeping CPUs. Some IRQs are kernel-managed and reject writes
# with EPERM even as root.
# Don't pin NIC queue IRQs. Pinning them serializes packet processing, and for
# S3 tests like fineweb-s3 network is the bottlenenck.
declare -A NET_IRQS=()
bench_cpu_arr=()
while IFS= read -r cpu; do bench_cpu_arr+=("$cpu"); done < <(expand_cpulist "$BENCH_CPUS")
i=0
for msi in /sys/class/net/*/device/msi_irqs/*; do
[[ -e "$msi" && ${#bench_cpu_arr[@]} -gt 0 ]] || continue
irq="${msi##*/}"
NET_IRQS["$irq"]=1
echo "${bench_cpu_arr[i % ${#bench_cpu_arr[@]}]}" > "/proc/irq/$irq/smp_affinity_list" 2>/dev/null || true
i=$((i + 1))
done

# Pin all non-NIC queue IRQs to housekeeping CPUs. Some IRQs are kernel-managed
# and reject writes with EPERM even as root.
for f in /proc/irq/[0-9]*/smp_affinity_list; do
irq="${f#/proc/irq/}"
irq="${irq%%/*}"
[[ -n "${NET_IRQS[$irq]:-}" ]] && continue
echo "$HOUSEKEEPING_CPUS" > "$f" 2>/dev/null || true
done

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