gotosocial/vendor/github.com/cilium/ebpf/link/syscalls.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

173 lines
4 KiB
Go

package link
import (
"errors"
"unsafe"
"github.com/cilium/ebpf"
"github.com/cilium/ebpf/asm"
"github.com/cilium/ebpf/internal"
"github.com/cilium/ebpf/internal/unix"
)
// Type is the kind of link.
type Type uint32
// Valid link types.
//
// Equivalent to enum bpf_link_type.
const (
UnspecifiedType Type = iota
RawTracepointType
TracingType
CgroupType
IterType
NetNsType
XDPType
)
var haveProgAttach = internal.FeatureTest("BPF_PROG_ATTACH", "4.10", func() error {
prog, err := ebpf.NewProgram(&ebpf.ProgramSpec{
Type: ebpf.CGroupSKB,
AttachType: ebpf.AttachCGroupInetIngress,
License: "MIT",
Instructions: asm.Instructions{
asm.Mov.Imm(asm.R0, 0),
asm.Return(),
},
})
if err != nil {
return internal.ErrNotSupported
}
// BPF_PROG_ATTACH was introduced at the same time as CGgroupSKB,
// so being able to load the program is enough to infer that we
// have the syscall.
prog.Close()
return nil
})
var haveProgAttachReplace = internal.FeatureTest("BPF_PROG_ATTACH atomic replacement", "5.5", func() error {
if err := haveProgAttach(); err != nil {
return err
}
prog, err := ebpf.NewProgram(&ebpf.ProgramSpec{
Type: ebpf.CGroupSKB,
AttachType: ebpf.AttachCGroupInetIngress,
License: "MIT",
Instructions: asm.Instructions{
asm.Mov.Imm(asm.R0, 0),
asm.Return(),
},
})
if err != nil {
return internal.ErrNotSupported
}
defer prog.Close()
// We know that we have BPF_PROG_ATTACH since we can load CGroupSKB programs.
// If passing BPF_F_REPLACE gives us EINVAL we know that the feature isn't
// present.
attr := internal.BPFProgAttachAttr{
// We rely on this being checked after attachFlags.
TargetFd: ^uint32(0),
AttachBpfFd: uint32(prog.FD()),
AttachType: uint32(ebpf.AttachCGroupInetIngress),
AttachFlags: uint32(flagReplace),
}
err = internal.BPFProgAttach(&attr)
if errors.Is(err, unix.EINVAL) {
return internal.ErrNotSupported
}
if errors.Is(err, unix.EBADF) {
return nil
}
return err
})
type bpfLinkCreateAttr struct {
progFd uint32
targetFd uint32
attachType ebpf.AttachType
flags uint32
}
func bpfLinkCreate(attr *bpfLinkCreateAttr) (*internal.FD, error) {
ptr, err := internal.BPF(internal.BPF_LINK_CREATE, unsafe.Pointer(attr), unsafe.Sizeof(*attr))
if err != nil {
return nil, err
}
return internal.NewFD(uint32(ptr)), nil
}
type bpfLinkUpdateAttr struct {
linkFd uint32
newProgFd uint32
flags uint32
oldProgFd uint32
}
func bpfLinkUpdate(attr *bpfLinkUpdateAttr) error {
_, err := internal.BPF(internal.BPF_LINK_UPDATE, unsafe.Pointer(attr), unsafe.Sizeof(*attr))
return err
}
var haveBPFLink = internal.FeatureTest("bpf_link", "5.7", func() error {
prog, err := ebpf.NewProgram(&ebpf.ProgramSpec{
Type: ebpf.CGroupSKB,
AttachType: ebpf.AttachCGroupInetIngress,
License: "MIT",
Instructions: asm.Instructions{
asm.Mov.Imm(asm.R0, 0),
asm.Return(),
},
})
if err != nil {
return internal.ErrNotSupported
}
defer prog.Close()
attr := bpfLinkCreateAttr{
// This is a hopefully invalid file descriptor, which triggers EBADF.
targetFd: ^uint32(0),
progFd: uint32(prog.FD()),
attachType: ebpf.AttachCGroupInetIngress,
}
_, err = bpfLinkCreate(&attr)
if errors.Is(err, unix.EINVAL) {
return internal.ErrNotSupported
}
if errors.Is(err, unix.EBADF) {
return nil
}
return err
})
type bpfIterCreateAttr struct {
linkFd uint32
flags uint32
}
func bpfIterCreate(attr *bpfIterCreateAttr) (*internal.FD, error) {
ptr, err := internal.BPF(internal.BPF_ITER_CREATE, unsafe.Pointer(attr), unsafe.Sizeof(*attr))
if err == nil {
return internal.NewFD(uint32(ptr)), nil
}
return nil, err
}
type bpfRawTracepointOpenAttr struct {
name internal.Pointer
fd uint32
_ uint32
}
func bpfRawTracepointOpen(attr *bpfRawTracepointOpenAttr) (*internal.FD, error) {
ptr, err := internal.BPF(internal.BPF_RAW_TRACEPOINT_OPEN, unsafe.Pointer(attr), unsafe.Sizeof(*attr))
if err == nil {
return internal.NewFD(uint32(ptr)), nil
}
return nil, err
}