Port filesystem metrics to VFS2.

PiperOrigin-RevId: 343196927

2 files changed, 93 insertions, 0 deletions

diff --git a/pkg/sentry/fsmetric/BUILD b/pkg/sentry/fsmetric/BUILD
new file mode 100644
index 000000000..4e86fbdd8
--- /dev/null
+++ b/pkg/sentry/fsmetric/BUILD
@@ -0,0 +1,10 @@
+load("//tools:defs.bzl", "go_library")
+
+licenses(["notice"])
+
+go_library(
+    name = "fsmetric",
+    srcs = ["fsmetric.go"],
+    visibility = ["//pkg/sentry:internal"],
+    deps = ["//pkg/metric"],
+)
diff --git a/pkg/sentry/fsmetric/fsmetric.go b/pkg/sentry/fsmetric/fsmetric.go
new file mode 100644
index 000000000..7e535b527
--- /dev/null
+++ b/pkg/sentry/fsmetric/fsmetric.go
@@ -0,0 +1,83 @@
+// Copyright 2020 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 fsmetric defines filesystem metrics that are used by both VFS1 and
+// VFS2.
+//
+// TODO(gvisor.dev/issue/1624): Once VFS1 is deleted, inline these metrics into
+// VFS2.
+package fsmetric
+
+import (
+	"time"
+
+	"gvisor.dev/gvisor/pkg/metric"
+)
+
+// RecordWaitTime enables the ReadWait, GoferReadWait9P, GoferReadWaitHost, and
+// TmpfsReadWait metrics. Enabling this comes at a CPU cost due to performing
+// three clock reads per read call.
+//
+// Note that this is only performed in the direct read path, and may not be
+// consistently applied for other forms of reads, such as splice.
+var RecordWaitTime = false
+
+// Metrics that apply to all filesystems.
+var (
+	Opens    = metric.MustCreateNewUint64Metric("/fs/opens", false /* sync */, "Number of file opens.")
+	Reads    = metric.MustCreateNewUint64Metric("/fs/reads", false /* sync */, "Number of file reads.")
+	ReadWait = metric.MustCreateNewUint64NanosecondsMetric("/fs/read_wait", false /* sync */, "Time waiting on file reads, in nanoseconds.")
+)
+
+// Metrics that only apply to fs/gofer and fsimpl/gofer.
+var (
+	GoferOpensWX      = metric.MustCreateNewUint64Metric("/gofer/opened_write_execute_file", true /* sync */, "Number of times a executable file was opened writably from a gofer.")
+	GoferOpens9P      = metric.MustCreateNewUint64Metric("/gofer/opens_9p", false /* sync */, "Number of times a file was opened from a gofer and did not have a host file descriptor.")
+	GoferOpensHost    = metric.MustCreateNewUint64Metric("/gofer/opens_host", false /* sync */, "Number of times a file was opened from a gofer and did have a host file descriptor.")
+	GoferReads9P      = metric.MustCreateNewUint64Metric("/gofer/reads_9p", false /* sync */, "Number of 9P file reads from a gofer.")
+	GoferReadWait9P   = metric.MustCreateNewUint64NanosecondsMetric("/gofer/read_wait_9p", false /* sync */, "Time waiting on 9P file reads from a gofer, in nanoseconds.")
+	GoferReadsHost    = metric.MustCreateNewUint64Metric("/gofer/reads_host", false /* sync */, "Number of host file reads from a gofer.")
+	GoferReadWaitHost = metric.MustCreateNewUint64NanosecondsMetric("/gofer/read_wait_host", false /* sync */, "Time waiting on host file reads from a gofer, in nanoseconds.")
+)
+
+// Metrics that only apply to fs/tmpfs and fsimpl/tmpfs.
+var (
+	TmpfsOpensRO  = metric.MustCreateNewUint64Metric("/in_memory_file/opens_ro", false /* sync */, "Number of times an in-memory file was opened in read-only mode.")
+	TmpfsOpensW   = metric.MustCreateNewUint64Metric("/in_memory_file/opens_w", false /* sync */, "Number of times an in-memory file was opened in write mode.")
+	TmpfsReads    = metric.MustCreateNewUint64Metric("/in_memory_file/reads", false /* sync */, "Number of in-memory file reads.")
+	TmpfsReadWait = metric.MustCreateNewUint64NanosecondsMetric("/in_memory_file/read_wait", false /* sync */, "Time waiting on in-memory file reads, in nanoseconds.")
+)
+
+// StartReadWait indicates the beginning of a file read.
+func StartReadWait() time.Time {
+	if !RecordWaitTime {
+		return time.Time{}
+	}
+	return time.Now()
+}
+
+// FinishReadWait indicates the end of a file read whose time is accounted by
+// m. start must be the value returned by the corresponding call to
+// StartReadWait.
+//
+// FinishReadWait is marked nosplit for performance since it's often called
+// from defer statements, which prevents it from being inlined
+// (https://github.com/golang/go/issues/38471).
+//go:nosplit
+func FinishReadWait(m *metric.Uint64Metric, start time.Time) {
+	if !RecordWaitTime {
+		return
+	}
+	m.IncrementBy(uint64(time.Since(start).Nanoseconds()))
+}