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-rw-r--r--pkg/sentry/vfs/mount_test.go465
1 files changed, 465 insertions, 0 deletions
diff --git a/pkg/sentry/vfs/mount_test.go b/pkg/sentry/vfs/mount_test.go
new file mode 100644
index 000000000..f394d7483
--- /dev/null
+++ b/pkg/sentry/vfs/mount_test.go
@@ -0,0 +1,465 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package vfs
+
+import (
+ "fmt"
+ "runtime"
+ "sync"
+ "testing"
+)
+
+func TestMountTableLookupEmpty(t *testing.T) {
+ var mt mountTable
+ mt.Init()
+
+ parent := &Mount{}
+ point := &Dentry{}
+ if m := mt.Lookup(parent, point); m != nil {
+ t.Errorf("empty mountTable lookup: got %p, wanted nil", m)
+ }
+}
+
+func TestMountTableInsertLookup(t *testing.T) {
+ var mt mountTable
+ mt.Init()
+
+ mount := &Mount{}
+ mount.storeKey(&Mount{}, &Dentry{})
+ mt.Insert(mount)
+
+ if m := mt.Lookup(mount.parent(), mount.point()); m != mount {
+ t.Errorf("mountTable positive lookup: got %p, wanted %p", m, mount)
+ }
+
+ otherParent := &Mount{}
+ if m := mt.Lookup(otherParent, mount.point()); m != nil {
+ t.Errorf("mountTable lookup with wrong mount parent: got %p, wanted nil", m)
+ }
+ otherPoint := &Dentry{}
+ if m := mt.Lookup(mount.parent(), otherPoint); m != nil {
+ t.Errorf("mountTable lookup with wrong mount point: got %p, wanted nil", m)
+ }
+}
+
+// TODO: concurrent lookup/insertion/removal
+
+// must be powers of 2
+var benchNumMounts = []int{1 << 2, 1 << 5, 1 << 8}
+
+// For all of the following:
+//
+// - BenchmarkMountTableFoo tests usage pattern "Foo" for mountTable.
+//
+// - BenchmarkMountMapFoo tests usage pattern "Foo" for a
+// sync.RWMutex-protected map. (Mutator benchmarks do not use a RWMutex, since
+// mountTable also requires external synchronization between mutators.)
+//
+// - BenchmarkMountSyncMapFoo tests usage pattern "Foo" for a sync.Map.
+//
+// ParallelLookup is by far the most common and performance-sensitive operation
+// for this application. NegativeLookup is also important, but less so (only
+// relevant with multiple mount namespaces and significant differences in
+// mounts between them). Insertion and removal are benchmarked for
+// completeness.
+const enableComparativeBenchmarks = false
+
+func newBenchMount() *Mount {
+ mount := &Mount{}
+ mount.storeKey(&Mount{}, &Dentry{})
+ return mount
+}
+
+func vdkey(mnt *Mount) VirtualDentry {
+ parent, point := mnt.loadKey()
+ return VirtualDentry{
+ mount: parent,
+ dentry: point,
+ }
+}
+
+func BenchmarkMountTableParallelLookup(b *testing.B) {
+ for numG, maxG := 1, runtime.GOMAXPROCS(0); numG >= 0 && numG <= maxG; numG *= 2 {
+ for _, numMounts := range benchNumMounts {
+ desc := fmt.Sprintf("%dx%d", numG, numMounts)
+ b.Run(desc, func(b *testing.B) {
+ var mt mountTable
+ mt.Init()
+ keys := make([]VirtualDentry, 0, numMounts)
+ for i := 0; i < numMounts; i++ {
+ mount := newBenchMount()
+ mt.Insert(mount)
+ keys = append(keys, vdkey(mount))
+ }
+
+ var ready sync.WaitGroup
+ begin := make(chan struct{})
+ var end sync.WaitGroup
+ for g := 0; g < numG; g++ {
+ ready.Add(1)
+ end.Add(1)
+ go func() {
+ defer end.Done()
+ ready.Done()
+ <-begin
+ for i := 0; i < b.N; i++ {
+ k := keys[i&(numMounts-1)]
+ m := mt.Lookup(k.mount, k.dentry)
+ if m == nil {
+ b.Fatalf("lookup failed")
+ }
+ if parent := m.parent(); parent != k.mount {
+ b.Fatalf("lookup returned mount with parent %p, wanted %p", parent, k.mount)
+ }
+ if point := m.point(); point != k.dentry {
+ b.Fatalf("lookup returned mount with point %p, wanted %p", point, k.dentry)
+ }
+ }
+ }()
+ }
+
+ ready.Wait()
+ b.ResetTimer()
+ close(begin)
+ end.Wait()
+ })
+ }
+ }
+}
+
+func BenchmarkMountMapParallelLookup(b *testing.B) {
+ if !enableComparativeBenchmarks {
+ b.Skipf("comparative benchmarks are disabled")
+ }
+
+ for numG, maxG := 1, runtime.GOMAXPROCS(0); numG >= 0 && numG <= maxG; numG *= 2 {
+ for _, numMounts := range benchNumMounts {
+ desc := fmt.Sprintf("%dx%d", numG, numMounts)
+ b.Run(desc, func(b *testing.B) {
+ var mu sync.RWMutex
+ ms := make(map[VirtualDentry]*Mount)
+ keys := make([]VirtualDentry, 0, numMounts)
+ for i := 0; i < numMounts; i++ {
+ mount := newBenchMount()
+ key := vdkey(mount)
+ ms[key] = mount
+ keys = append(keys, key)
+ }
+
+ var ready sync.WaitGroup
+ begin := make(chan struct{})
+ var end sync.WaitGroup
+ for g := 0; g < numG; g++ {
+ ready.Add(1)
+ end.Add(1)
+ go func() {
+ defer end.Done()
+ ready.Done()
+ <-begin
+ for i := 0; i < b.N; i++ {
+ k := keys[i&(numMounts-1)]
+ mu.RLock()
+ m := ms[k]
+ mu.RUnlock()
+ if m == nil {
+ b.Fatalf("lookup failed")
+ }
+ if parent := m.parent(); parent != k.mount {
+ b.Fatalf("lookup returned mount with parent %p, wanted %p", parent, k.mount)
+ }
+ if point := m.point(); point != k.dentry {
+ b.Fatalf("lookup returned mount with point %p, wanted %p", point, k.dentry)
+ }
+ }
+ }()
+ }
+
+ ready.Wait()
+ b.ResetTimer()
+ close(begin)
+ end.Wait()
+ })
+ }
+ }
+}
+
+func BenchmarkMountSyncMapParallelLookup(b *testing.B) {
+ if !enableComparativeBenchmarks {
+ b.Skipf("comparative benchmarks are disabled")
+ }
+
+ for numG, maxG := 1, runtime.GOMAXPROCS(0); numG >= 0 && numG <= maxG; numG *= 2 {
+ for _, numMounts := range benchNumMounts {
+ desc := fmt.Sprintf("%dx%d", numG, numMounts)
+ b.Run(desc, func(b *testing.B) {
+ var ms sync.Map
+ keys := make([]VirtualDentry, 0, numMounts)
+ for i := 0; i < numMounts; i++ {
+ mount := newBenchMount()
+ key := vdkey(mount)
+ ms.Store(key, mount)
+ keys = append(keys, key)
+ }
+
+ var ready sync.WaitGroup
+ begin := make(chan struct{})
+ var end sync.WaitGroup
+ for g := 0; g < numG; g++ {
+ ready.Add(1)
+ end.Add(1)
+ go func() {
+ defer end.Done()
+ ready.Done()
+ <-begin
+ for i := 0; i < b.N; i++ {
+ k := keys[i&(numMounts-1)]
+ mi, ok := ms.Load(k)
+ if !ok {
+ b.Fatalf("lookup failed")
+ }
+ m := mi.(*Mount)
+ if parent := m.parent(); parent != k.mount {
+ b.Fatalf("lookup returned mount with parent %p, wanted %p", parent, k.mount)
+ }
+ if point := m.point(); point != k.dentry {
+ b.Fatalf("lookup returned mount with point %p, wanted %p", point, k.dentry)
+ }
+ }
+ }()
+ }
+
+ ready.Wait()
+ b.ResetTimer()
+ close(begin)
+ end.Wait()
+ })
+ }
+ }
+}
+
+func BenchmarkMountTableNegativeLookup(b *testing.B) {
+ for _, numMounts := range benchNumMounts {
+ desc := fmt.Sprintf("%d", numMounts)
+ b.Run(desc, func(b *testing.B) {
+ var mt mountTable
+ mt.Init()
+ for i := 0; i < numMounts; i++ {
+ mt.Insert(newBenchMount())
+ }
+ negkeys := make([]VirtualDentry, 0, numMounts)
+ for i := 0; i < numMounts; i++ {
+ negkeys = append(negkeys, VirtualDentry{
+ mount: &Mount{},
+ dentry: &Dentry{},
+ })
+ }
+
+ b.ResetTimer()
+ for i := 0; i < b.N; i++ {
+ k := negkeys[i&(numMounts-1)]
+ m := mt.Lookup(k.mount, k.dentry)
+ if m != nil {
+ b.Fatalf("lookup got %p, wanted nil", m)
+ }
+ }
+ })
+ }
+}
+
+func BenchmarkMountMapNegativeLookup(b *testing.B) {
+ if !enableComparativeBenchmarks {
+ b.Skipf("comparative benchmarks are disabled")
+ }
+
+ for _, numMounts := range benchNumMounts {
+ desc := fmt.Sprintf("%d", numMounts)
+ b.Run(desc, func(b *testing.B) {
+ var mu sync.RWMutex
+ ms := make(map[VirtualDentry]*Mount)
+ for i := 0; i < numMounts; i++ {
+ mount := newBenchMount()
+ ms[vdkey(mount)] = mount
+ }
+ negkeys := make([]VirtualDentry, 0, numMounts)
+ for i := 0; i < numMounts; i++ {
+ negkeys = append(negkeys, VirtualDentry{
+ mount: &Mount{},
+ dentry: &Dentry{},
+ })
+ }
+
+ b.ResetTimer()
+ for i := 0; i < b.N; i++ {
+ k := negkeys[i&(numMounts-1)]
+ mu.RLock()
+ m := ms[k]
+ mu.RUnlock()
+ if m != nil {
+ b.Fatalf("lookup got %p, wanted nil", m)
+ }
+ }
+ })
+ }
+}
+
+func BenchmarkMountSyncMapNegativeLookup(b *testing.B) {
+ if !enableComparativeBenchmarks {
+ b.Skipf("comparative benchmarks are disabled")
+ }
+
+ for _, numMounts := range benchNumMounts {
+ desc := fmt.Sprintf("%d", numMounts)
+ b.Run(desc, func(b *testing.B) {
+ var ms sync.Map
+ for i := 0; i < numMounts; i++ {
+ mount := newBenchMount()
+ ms.Store(vdkey(mount), mount)
+ }
+ negkeys := make([]VirtualDentry, 0, numMounts)
+ for i := 0; i < numMounts; i++ {
+ negkeys = append(negkeys, VirtualDentry{
+ mount: &Mount{},
+ dentry: &Dentry{},
+ })
+ }
+
+ b.ResetTimer()
+ for i := 0; i < b.N; i++ {
+ k := negkeys[i&(numMounts-1)]
+ m, _ := ms.Load(k)
+ if m != nil {
+ b.Fatalf("lookup got %p, wanted nil", m)
+ }
+ }
+ })
+ }
+}
+
+func BenchmarkMountTableInsert(b *testing.B) {
+ // Preallocate Mounts so that allocation time isn't included in the
+ // benchmark.
+ mounts := make([]*Mount, 0, b.N)
+ for i := 0; i < b.N; i++ {
+ mounts = append(mounts, newBenchMount())
+ }
+
+ var mt mountTable
+ mt.Init()
+ b.ResetTimer()
+ for i := range mounts {
+ mt.Insert(mounts[i])
+ }
+}
+
+func BenchmarkMountMapInsert(b *testing.B) {
+ if !enableComparativeBenchmarks {
+ b.Skipf("comparative benchmarks are disabled")
+ }
+
+ // Preallocate Mounts so that allocation time isn't included in the
+ // benchmark.
+ mounts := make([]*Mount, 0, b.N)
+ for i := 0; i < b.N; i++ {
+ mounts = append(mounts, newBenchMount())
+ }
+
+ ms := make(map[VirtualDentry]*Mount)
+ b.ResetTimer()
+ for i := range mounts {
+ mount := mounts[i]
+ ms[vdkey(mount)] = mount
+ }
+}
+
+func BenchmarkMountSyncMapInsert(b *testing.B) {
+ if !enableComparativeBenchmarks {
+ b.Skipf("comparative benchmarks are disabled")
+ }
+
+ // Preallocate Mounts so that allocation time isn't included in the
+ // benchmark.
+ mounts := make([]*Mount, 0, b.N)
+ for i := 0; i < b.N; i++ {
+ mounts = append(mounts, newBenchMount())
+ }
+
+ var ms sync.Map
+ b.ResetTimer()
+ for i := range mounts {
+ mount := mounts[i]
+ ms.Store(vdkey(mount), mount)
+ }
+}
+
+func BenchmarkMountTableRemove(b *testing.B) {
+ mounts := make([]*Mount, 0, b.N)
+ for i := 0; i < b.N; i++ {
+ mounts = append(mounts, newBenchMount())
+ }
+ var mt mountTable
+ mt.Init()
+ for i := range mounts {
+ mt.Insert(mounts[i])
+ }
+
+ b.ResetTimer()
+ for i := range mounts {
+ mt.Remove(mounts[i])
+ }
+}
+
+func BenchmarkMountMapRemove(b *testing.B) {
+ if !enableComparativeBenchmarks {
+ b.Skipf("comparative benchmarks are disabled")
+ }
+
+ mounts := make([]*Mount, 0, b.N)
+ for i := 0; i < b.N; i++ {
+ mounts = append(mounts, newBenchMount())
+ }
+ ms := make(map[VirtualDentry]*Mount)
+ for i := range mounts {
+ mount := mounts[i]
+ ms[vdkey(mount)] = mount
+ }
+
+ b.ResetTimer()
+ for i := range mounts {
+ mount := mounts[i]
+ delete(ms, vdkey(mount))
+ }
+}
+
+func BenchmarkMountSyncMapRemove(b *testing.B) {
+ if !enableComparativeBenchmarks {
+ b.Skipf("comparative benchmarks are disabled")
+ }
+
+ mounts := make([]*Mount, 0, b.N)
+ for i := 0; i < b.N; i++ {
+ mounts = append(mounts, newBenchMount())
+ }
+ var ms sync.Map
+ for i := range mounts {
+ mount := mounts[i]
+ ms.Store(vdkey(mount), mount)
+ }
+
+ b.ResetTimer()
+ for i := range mounts {
+ mount := mounts[i]
+ ms.Delete(vdkey(mount))
+ }
+}
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