Report task CPU usage through the cpuacct cgroup controller.

PiperOrigin-RevId: 366923274

4 files changed, 133 insertions, 7 deletions

diff --git a/pkg/sentry/fsimpl/cgroupfs/base.go b/pkg/sentry/fsimpl/cgroupfs/base.go
index 360bbb17d..39c1013e1 100644
--- a/pkg/sentry/fsimpl/cgroupfs/base.go
+++ b/pkg/sentry/fsimpl/cgroupfs/base.go
@@ -167,8 +167,8 @@ func (d *cgroupProcsData) Generate(ctx context.Context, buf *bytes.Buffer) error
 
 	pgids := make(map[kernel.ThreadID]struct{})
 
-	d.fs.tasksMu.Lock()
-	defer d.fs.tasksMu.Unlock()
+	d.fs.tasksMu.RLock()
+	defer d.fs.tasksMu.RUnlock()
 
 	for task := range d.ts {
 		// Map dedups pgid, since iterating over all tasks produces multiple
@@ -209,8 +209,8 @@ func (d *tasksData) Generate(ctx context.Context, buf *bytes.Buffer) error {
 
 	var pids []kernel.ThreadID
 
-	d.fs.tasksMu.Lock()
-	defer d.fs.tasksMu.Unlock()
+	d.fs.tasksMu.RLock()
+	defer d.fs.tasksMu.RUnlock()
 
 	for task := range d.ts {
 		if pid := currPidns.IDOfTask(task); pid != 0 {
diff --git a/pkg/sentry/fsimpl/cgroupfs/cgroupfs.go b/pkg/sentry/fsimpl/cgroupfs/cgroupfs.go
index 6061bace2..ca8caee5f 100644
--- a/pkg/sentry/fsimpl/cgroupfs/cgroupfs.go
+++ b/pkg/sentry/fsimpl/cgroupfs/cgroupfs.go
@@ -129,7 +129,7 @@ type filesystem struct {
 
 	// tasksMu serializes task membership changes across all cgroups within a
 	// filesystem.
-	tasksMu sync.Mutex `state:"nosave"`
+	tasksMu sync.RWMutex `state:"nosave"`
 }
 
 // Name implements vfs.FilesystemType.Name.
diff --git a/pkg/sentry/fsimpl/cgroupfs/cpuacct.go b/pkg/sentry/fsimpl/cgroupfs/cpuacct.go
index 0bb7f5c76..d4104a00e 100644
--- a/pkg/sentry/fsimpl/cgroupfs/cpuacct.go
+++ b/pkg/sentry/fsimpl/cgroupfs/cpuacct.go
@@ -15,9 +15,14 @@
 package cgroupfs
 
 import (
+	"bytes"
+	"fmt"
+
+	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+	"gvisor.dev/gvisor/pkg/sentry/usage"
 )
 
 // +stateify savable
@@ -34,6 +39,76 @@ func newCPUAcctController(fs *filesystem) *cpuacctController {
 }
 
 // AddControlFiles implements controller.AddControlFiles.
-func (c *cpuacctController) AddControlFiles(ctx context.Context, creds *auth.Credentials, _ *cgroupInode, contents map[string]kernfs.Inode) {
-	// This controller is currently intentionally empty.
+func (c *cpuacctController) AddControlFiles(ctx context.Context, creds *auth.Credentials, cg *cgroupInode, contents map[string]kernfs.Inode) {
+	cpuacctCG := &cpuacctCgroup{cg}
+	contents["cpuacct.stat"] = c.fs.newControllerFile(ctx, creds, &cpuacctStatData{cpuacctCG})
+	contents["cpuacct.usage"] = c.fs.newControllerFile(ctx, creds, &cpuacctUsageData{cpuacctCG})
+	contents["cpuacct.usage_user"] = c.fs.newControllerFile(ctx, creds, &cpuacctUsageUserData{cpuacctCG})
+	contents["cpuacct.usage_sys"] = c.fs.newControllerFile(ctx, creds, &cpuacctUsageSysData{cpuacctCG})
+}
+
+// +stateify savable
+type cpuacctCgroup struct {
+	*cgroupInode
+}
+
+func (c *cpuacctCgroup) collectCPUStats() usage.CPUStats {
+	var cs usage.CPUStats
+	c.fs.tasksMu.RLock()
+	// Note: This isn't very accurate, since the tasks are potentially
+	// still running as we accumulate their stats.
+	for t := range c.ts {
+		cs.Accumulate(t.CPUStats())
+	}
+	c.fs.tasksMu.RUnlock()
+	return cs
+}
+
+// +stateify savable
+type cpuacctStatData struct {
+	*cpuacctCgroup
+}
+
+// Generate implements vfs.DynamicBytesSource.Generate.
+func (d *cpuacctStatData) Generate(ctx context.Context, buf *bytes.Buffer) error {
+	cs := d.collectCPUStats()
+	fmt.Fprintf(buf, "user %d\n", linux.ClockTFromDuration(cs.UserTime))
+	fmt.Fprintf(buf, "system %d\n", linux.ClockTFromDuration(cs.SysTime))
+	return nil
+}
+
+// +stateify savable
+type cpuacctUsageData struct {
+	*cpuacctCgroup
+}
+
+// Generate implements vfs.DynamicBytesSource.Generate.
+func (d *cpuacctUsageData) Generate(ctx context.Context, buf *bytes.Buffer) error {
+	cs := d.collectCPUStats()
+	fmt.Fprintf(buf, "%d\n", cs.UserTime.Nanoseconds()+cs.SysTime.Nanoseconds())
+	return nil
+}
+
+// +stateify savable
+type cpuacctUsageUserData struct {
+	*cpuacctCgroup
+}
+
+// Generate implements vfs.DynamicBytesSource.Generate.
+func (d *cpuacctUsageUserData) Generate(ctx context.Context, buf *bytes.Buffer) error {
+	cs := d.collectCPUStats()
+	fmt.Fprintf(buf, "%d\n", cs.UserTime.Nanoseconds())
+	return nil
+}
+
+// +stateify savable
+type cpuacctUsageSysData struct {
+	*cpuacctCgroup
+}
+
+// Generate implements vfs.DynamicBytesSource.Generate.
+func (d *cpuacctUsageSysData) Generate(ctx context.Context, buf *bytes.Buffer) error {
+	cs := d.collectCPUStats()
+	fmt.Fprintf(buf, "%d\n", cs.SysTime.Nanoseconds())
+	return nil
 }
diff --git a/test/syscalls/linux/cgroup.cc b/test/syscalls/linux/cgroup.cc
index 3a51348ba..a1006a978 100644
--- a/test/syscalls/linux/cgroup.cc
+++ b/test/syscalls/linux/cgroup.cc
@@ -21,6 +21,7 @@
 #include "gtest/gtest.h"
 #include "absl/container/flat_hash_map.h"
 #include "absl/container/flat_hash_set.h"
+#include "absl/strings/str_split.h"
 #include "test/util/capability_util.h"
 #include "test/util/cgroup_util.h"
 #include "test/util/temp_path.h"
@@ -31,6 +32,7 @@ namespace testing {
 namespace {
 
 using ::testing::_;
+using ::testing::Ge;
 using ::testing::Gt;
 
 std::vector<std::string> known_controllers = {"cpu", "cpuset", "cpuacct",
@@ -206,6 +208,55 @@ TEST(CPUCgroup, ControlFilesHaveDefaultValues) {
               IsPosixErrorOkAndHolds(1024));
 }
 
+TEST(CPUAcctCgroup, CPUAcctUsage) {
+  SKIP_IF(!CgroupsAvailable());
+
+  Mounter m(ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()));
+  Cgroup c = ASSERT_NO_ERRNO_AND_VALUE(m.MountCgroupfs("cpuacct"));
+
+  const int64_t usage =
+      ASSERT_NO_ERRNO_AND_VALUE(c.ReadIntegerControlFile("cpuacct.usage"));
+  const int64_t usage_user =
+      ASSERT_NO_ERRNO_AND_VALUE(c.ReadIntegerControlFile("cpuacct.usage_user"));
+  const int64_t usage_sys =
+      ASSERT_NO_ERRNO_AND_VALUE(c.ReadIntegerControlFile("cpuacct.usage_sys"));
+
+  EXPECT_GE(usage, 0);
+  EXPECT_GE(usage_user, 0);
+  EXPECT_GE(usage_sys, 0);
+
+  EXPECT_GE(usage_user + usage_sys, usage);
+}
+
+TEST(CPUAcctCgroup, CPUAcctStat) {
+  SKIP_IF(!CgroupsAvailable());
+
+  Mounter m(ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()));
+  Cgroup c = ASSERT_NO_ERRNO_AND_VALUE(m.MountCgroupfs("cpuacct"));
+
+  std::string stat =
+      ASSERT_NO_ERRNO_AND_VALUE(c.ReadControlFile("cpuacct.stat"));
+
+  // We're expecting the contents of "cpuacct.stat" to look similar to this:
+  //
+  // user 377986
+  // system 220662
+
+  std::vector<absl::string_view> lines =
+      absl::StrSplit(stat, '\n', absl::SkipEmpty());
+  ASSERT_EQ(lines.size(), 2);
+
+  std::vector<absl::string_view> user_tokens =
+      StrSplit(lines[0], absl::ByChar(' '));
+  EXPECT_EQ(user_tokens[0], "user");
+  EXPECT_THAT(Atoi<int64_t>(user_tokens[1]), IsPosixErrorOkAndHolds(Ge(0)));
+
+  std::vector<absl::string_view> sys_tokens =
+      StrSplit(lines[1], absl::ByChar(' '));
+  EXPECT_EQ(sys_tokens[0], "system");
+  EXPECT_THAT(Atoi<int64_t>(sys_tokens[1]), IsPosixErrorOkAndHolds(Ge(0)));
+}
+
 TEST(ProcCgroups, Empty) {
   SKIP_IF(!CgroupsAvailable());