gotosocial/vendor/github.com/containerd/cgroups/v2/ebpf.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

96 lines
2.5 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 v2
import (
"fmt"
"github.com/cilium/ebpf"
"github.com/cilium/ebpf/asm"
"github.com/cilium/ebpf/link"
"github.com/opencontainers/runtime-spec/specs-go"
"golang.org/x/sys/unix"
)
// LoadAttachCgroupDeviceFilter installs eBPF device filter program to /sys/fs/cgroup/<foo> directory.
//
// Requires the system to be running in cgroup2 unified-mode with kernel >= 4.15 .
//
// https://github.com/torvalds/linux/commit/ebc614f687369f9df99828572b1d85a7c2de3d92
func LoadAttachCgroupDeviceFilter(insts asm.Instructions, license string, dirFD int) (func() error, error) {
nilCloser := func() error {
return nil
}
spec := &ebpf.ProgramSpec{
Type: ebpf.CGroupDevice,
Instructions: insts,
License: license,
}
prog, err := ebpf.NewProgram(spec)
if err != nil {
return nilCloser, err
}
err = link.RawAttachProgram(link.RawAttachProgramOptions{
Target: dirFD,
Program: prog,
Attach: ebpf.AttachCGroupDevice,
Flags: unix.BPF_F_ALLOW_MULTI,
})
if err != nil {
return nilCloser, fmt.Errorf("failed to call BPF_PROG_ATTACH (BPF_CGROUP_DEVICE, BPF_F_ALLOW_MULTI): %w", err)
}
closer := func() error {
err = link.RawDetachProgram(link.RawDetachProgramOptions{
Target: dirFD,
Program: prog,
Attach: ebpf.AttachCGroupDevice,
})
if err != nil {
return fmt.Errorf("failed to call BPF_PROG_DETACH (BPF_CGROUP_DEVICE): %w", err)
}
return nil
}
return closer, nil
}
func isRWM(cgroupPermissions string) bool {
r := false
w := false
m := false
for _, rn := range cgroupPermissions {
switch rn {
case 'r':
r = true
case 'w':
w = true
case 'm':
m = true
}
}
return r && w && m
}
// the logic is from runc
// https://github.com/opencontainers/runc/blob/master/libcontainer/cgroups/fs/devices_v2.go#L44
func canSkipEBPFError(devices []specs.LinuxDeviceCgroup) bool {
for _, dev := range devices {
if dev.Allow || !isRWM(dev.Access) {
return false
}
}
return true
}