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Merged
Michal-Leszczynski merged 1 commit into from
Aug 6, 2026
Merged

Don't return an error on all busy CPUs #4893

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12 changes: 2 additions & 10 deletions v3/pkg/util/cpuset/cpuset_linux.go
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Copyright (C) 2017 ScyllaDB
// Copyright (C) 2026 ScyllaDB
//go:build linux
// +build linux

Expand All @@ -14,10 +14,7 @@ import (
"golang.org/x/sys/unix"
)

// AvailableCPUs returns a list of CPUs of length wantCPUs that does not contain
// any of the busyCPUs. If the conditions cannot be met error is returned.
// AvailableCPUs selects the CPUs with the highest available indexes to offload
// shard 0...
// AvailableCPUs returns a list of CPUs that does not contain any of the busyCPUs.
func AvailableCPUs(busyCPUs []int) ([]int, error) {
var cpus unix.CPUSet
if err := unix.SchedGetaffinity(os.Getpid(), &cpus); err != nil {
Expand All @@ -27,11 +24,6 @@ func AvailableCPUs(busyCPUs []int) ([]int, error) {
cpus.Clear(c)
}

n := cpus.Count()
if n == 0 {
return nil, errors.Errorf("no available CPUs")
}

return cpulist(&cpus), nil
}

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17 changes: 17 additions & 0 deletions v3/pkg/util/cpuset/cpuset_linux_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,23 @@ func TestAvailableCPUs(t *testing.T) {
}
}

func TestAvailableCPUsAllBusy(t *testing.T) {
t.Parallel()

var cpus unix.CPUSet
if err := unix.SchedGetaffinity(0, &cpus); err != nil {
t.Fatal(err)
}

a, err := AvailableCPUs(cpulist(&cpus))
if err != nil {
t.Fatal(err)
}
if len(a) != 0 {
t.Fatalf("expected no available CPUs, got %d", len(a))
}
}

func TestSchedSetAffinity(t *testing.T) {
var cpus unix.CPUSet
if err := unix.SchedGetaffinity(0, &cpus); err != nil {
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