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https://github.com/slackhq/nebula.git
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JackDoan
10e9514e44
Each listenIn goroutine locks its OS thread and pins it to one CPU (sched_setaffinity), so every UDP send from that goroutine leaves through the same XPS-selected NIC TX ring instead of being sprayed across rings and reordered. On by default via tun.pin_threads; queue i pins to the i-th entry of the process's allowed CPU set (respecting cpuset/taskset masks, whose IDs are often not 0..NumCPU-1), or to an explicit tun.cpu_affinity list, validated against that same allowed set. Linux only; pinning is a no-op elsewhere. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
52 lines
1.6 KiB
Go
52 lines
1.6 KiB
Go
package nebula
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import (
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"testing"
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"github.com/slackhq/nebula/config"
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"github.com/slackhq/nebula/test"
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"github.com/slackhq/nebula/util"
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"github.com/stretchr/testify/assert"
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)
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func TestParseCpuAffinity(t *testing.T) {
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l := test.NewLogger()
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// newConfig returns a config.C with tun.cpu_affinity set to v. A nil v
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// leaves the key unset.
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newConfig := func(v any) *config.C {
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c := config.NewC(l)
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if v != nil {
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c.Settings["tun"] = map[string]any{"cpu_affinity": v}
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}
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return c
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}
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// unset -> nil (listenIn falls back to spreading across the allowed set)
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assert.Nil(t, parseCpuAffinity(newConfig(nil), l, 1))
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// Pick a CPU we're actually allowed to run on so a valid list survives
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// validation regardless of the host's affinity mask.
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allowed, _ := util.AllowedCPUs()
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validCPU := 0
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if len(allowed) > 0 {
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validCPU = allowed[0]
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}
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// valid list -> parsed through unchanged
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assert.Equal(t, []int{validCPU, validCPU}, parseCpuAffinity(newConfig([]any{validCPU, validCPU}), l, 2))
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// a negative entry is out of range on every platform -> disables the override
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assert.Nil(t, parseCpuAffinity(newConfig([]any{validCPU, -1}), l, 2))
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// a non-integer entry -> disables the override
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assert.Nil(t, parseCpuAffinity(newConfig([]any{validCPU, "not-a-cpu"}), l, 2))
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// a CPU id outside the allowed set -> disables the override. Only assertable
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// where we can enumerate the allowed set (e.g. linux); 1<<20 is far beyond
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// any representable CPU id so it can never be in the mask.
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if len(allowed) > 0 {
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assert.Nil(t, parseCpuAffinity(newConfig([]any{1 << 20}), l, 1))
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}
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}
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