gotosocial/vendor/github.com/containerd/cgroups/cpuset.go
Daniele Sluijters acc333c40b
[feature] Inherit resource limits from cgroups (#1336)
When GTS is running in a container runtime which has configured CPU or
memory limits or under an init system that uses cgroups to impose CPU
and memory limits the values the Go runtime sees for GOMAXPROCS and
GOMEMLIMIT are still based on the host resources, not the cgroup.

At least for the throttling middlewares which use GOMAXPROCS to
configure their queue size, this can result in GTS running with values
too big compared to the resources that will actuall be available to it.

This introduces 2 dependencies which can pick up resource contraints
from the current cgroup and tune the Go runtime accordingly. This should
result in the different queues being appropriately sized and in general
more predictable performance. These dependencies are a no-op on
non-Linux systems or if running in a cgroup that doesn't set a limit on
CPU or memory.

The automatic tuning of GOMEMLIMIT can be disabled by either explicitly
setting GOMEMLIMIT yourself or by setting AUTOMEMLIMIT=off. The
automatic tuning of GOMAXPROCS can similarly be counteracted by setting
GOMAXPROCS yourself.
2023-01-17 20:59:04 +00:00

159 lines
3.8 KiB
Go

/*
Copyright The containerd 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 cgroups
import (
"bytes"
"fmt"
"io/ioutil"
"os"
"path/filepath"
specs "github.com/opencontainers/runtime-spec/specs-go"
)
func NewCpuset(root string) *cpusetController {
return &cpusetController{
root: filepath.Join(root, string(Cpuset)),
}
}
type cpusetController struct {
root string
}
func (c *cpusetController) Name() Name {
return Cpuset
}
func (c *cpusetController) Path(path string) string {
return filepath.Join(c.root, path)
}
func (c *cpusetController) Create(path string, resources *specs.LinuxResources) error {
if err := c.ensureParent(c.Path(path), c.root); err != nil {
return err
}
if err := os.MkdirAll(c.Path(path), defaultDirPerm); err != nil {
return err
}
if err := c.copyIfNeeded(c.Path(path), filepath.Dir(c.Path(path))); err != nil {
return err
}
if resources.CPU != nil {
for _, t := range []struct {
name string
value string
}{
{
name: "cpus",
value: resources.CPU.Cpus,
},
{
name: "mems",
value: resources.CPU.Mems,
},
} {
if t.value != "" {
if err := retryingWriteFile(
filepath.Join(c.Path(path), "cpuset."+t.name),
[]byte(t.value),
defaultFilePerm,
); err != nil {
return err
}
}
}
}
return nil
}
func (c *cpusetController) Update(path string, resources *specs.LinuxResources) error {
return c.Create(path, resources)
}
func (c *cpusetController) getValues(path string) (cpus []byte, mems []byte, err error) {
if cpus, err = ioutil.ReadFile(filepath.Join(path, "cpuset.cpus")); err != nil && !os.IsNotExist(err) {
return
}
if mems, err = ioutil.ReadFile(filepath.Join(path, "cpuset.mems")); err != nil && !os.IsNotExist(err) {
return
}
return cpus, mems, nil
}
// ensureParent makes sure that the parent directory of current is created
// and populated with the proper cpus and mems files copied from
// it's parent.
func (c *cpusetController) ensureParent(current, root string) error {
parent := filepath.Dir(current)
if _, err := filepath.Rel(root, parent); err != nil {
return nil
}
// Avoid infinite recursion.
if parent == current {
return fmt.Errorf("cpuset: cgroup parent path outside cgroup root")
}
if cleanPath(parent) != root {
if err := c.ensureParent(parent, root); err != nil {
return err
}
}
if err := os.MkdirAll(current, defaultDirPerm); err != nil {
return err
}
return c.copyIfNeeded(current, parent)
}
// copyIfNeeded copies the cpuset.cpus and cpuset.mems from the parent
// directory to the current directory if the file's contents are 0
func (c *cpusetController) copyIfNeeded(current, parent string) error {
var (
err error
currentCpus, currentMems []byte
parentCpus, parentMems []byte
)
if currentCpus, currentMems, err = c.getValues(current); err != nil {
return err
}
if parentCpus, parentMems, err = c.getValues(parent); err != nil {
return err
}
if isEmpty(currentCpus) {
if err := retryingWriteFile(
filepath.Join(current, "cpuset.cpus"),
parentCpus,
defaultFilePerm,
); err != nil {
return err
}
}
if isEmpty(currentMems) {
if err := retryingWriteFile(
filepath.Join(current, "cpuset.mems"),
parentMems,
defaultFilePerm,
); err != nil {
return err
}
}
return nil
}
func isEmpty(b []byte) bool {
return len(bytes.Trim(b, "\n")) == 0
}