gvisor/test/benchmarks/README.md

# Benchmark tools

This package and subpackages are for running macro benchmarks on `runsc`. They
are meant to replace the previous //benchmarks benchmark-tools written in
python.

Benchmarks are meant to look like regular golang benchmarks using the testing.B
library.

## Setup

To run benchmarks you will need:

*   Docker installed (17.09.0 or greater).

The easiest way to setup runsc for running benchmarks is to use the make file.
From the root directory:

*   Download images: `make load-all-images`
*   Install runsc suitable for benchmarking, which should probably not have
    strace or debug logs enabled. For example:`make configure RUNTIME=myrunsc
    ARGS=--platform=kvm`.
*   Restart docker: `sudo service docker restart`

You should now have a runtime with the following options configured in
`/etc/docker/daemon.json`

```
"myrunsc": {
            "path": "/tmp/myrunsc/runsc",
            "runtimeArgs": [
                "--debug-log",
                "/tmp/bench/logs/runsc.log.%TEST%.%TIMESTAMP%.%COMMAND%",
                "--platform=kvm"
            ]
        },

```

This runtime has been configured with a debugging off and strace logs off and is
using kvm for demonstration.

## Running benchmarks

Given the runtime above runtime `myrunsc`, run benchmarks with the following:

```
make sudo TARGETS=//path/to:target ARGS="--runtime=myrunsc -test.v \
  -test.bench=." OPTIONS="-c opt
```

For example, to run only the Iperf tests:

```
make sudo TARGETS=//test/benchmarks/network:network_test \
  ARGS="--runtime=myrunsc -test.v -test.bench=Iperf" OPTIONS="-c opt"
```

Benchmarks are run with root as some benchmarks require root privileges to do
things like drop caches.

## Writing benchmarks

Benchmarks consist of docker images as Dockerfiles and golang testing.B
benchmarks.

### Dockerfiles:

*   Are stored at //images.
*   New Dockerfiles go in an appropriately named directory at
    `//images/benchmarks/my-cool-dockerfile`.
*   Dockerfiles for benchmarks should:
    *   Use explicitly versioned packages.
    *   Not use ENV and CMD statements...it is easy to add these in the API.
*   Note: A common pattern for getting access to a tmpfs mount is to copy files
    there after container start. See: //test/benchmarks/build/bazel_test.go. You
    can also make your own with `RunOpts.Mounts`.

### testing.B packages

In general, benchmarks should look like this:

```golang

var h harness.Harness

func BenchmarkMyCoolOne(b *testing.B) {
  machine, err := h.GetMachine()
  // check err
  defer machine.CleanUp()

  ctx := context.Background()
  container := machine.GetContainer(ctx, b)
  defer container.CleanUp(ctx)

  b.ResetTimer()

  //Respect b.N.
  for i := 0; i < b.N; i++ {
    out, err := container.Run(ctx, dockerutil.RunOpts{
      Image: "benchmarks/my-cool-image",
      Env: []string{"MY_VAR=awesome"},
      other options...see dockerutil
    }, "sh", "-c", "echo MY_VAR")
    //check err
    b.StopTimer()

    // Do parsing and reporting outside of the timer.
    number := parseMyMetric(out)
    b.ReportMetric(number, "my-cool-custom-metric")

    b.StartTimer()
  }
}

func TestMain(m *testing.M) {
    h.Init()
    os.Exit(m.Run())
}
```

Some notes on the above:

*   The harness is initiated in the TestMain method and made global to test
    module. The harness will handle any presetup that needs to happen with
    flags, remote virtual machines (eventually), and other services.
*   Respect `b.N` in that users of the benchmark may want to "run for an hour"
    or something of the sort.
*   Use the `b.ReportMetric()` method to report custom metrics.
*   Set the timer if time is useful for reporting. There isn't a way to turn off
    default metrics in testing.B (B/op, allocs/op, ns/op).
*   Take a look at dockerutil at //pkg/test/dockerutil to see all methods
    available from containers. The API is based on the "official"
    [docker API for golang](https://pkg.go.dev/mod/github.com/docker/docker).
*   `harness.GetMachine()` marks how many machines this tests needs. If you have
    a client and server and to mark them as multiple machines, call
    `harness.GetMachine()` twice.

## Profiling

For profiling, the runtime is required to have the `--profile` flag enabled.
This flag loosens seccomp filters so that the runtime can write profile data to
disk. This configuration is not recommended for production.

*   Install runsc with the `--profile` flag: `make configure RUNTIME=myrunsc
    ARGS="--profile --platform=kvm --vfs2"`. The kvm and vfs2 flags are not
    required, but are included for demonstration.
*   Restart docker: `sudo service docker restart`

To run and generate CPU profiles fs_test test run:

```
make sudo TARGETS=//test/benchmarks/fs:fs_test \
  ARGS="--runtime=myrunsc -test.v -test.bench=. --pprof-cpu" OPTIONS="-c opt"
```

Profiles would be at: `/tmp/profile/myrunsc/CONTAINERNAME/cpu.pprof`