mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-05-20 09:18:13 +00:00
acc333c40b
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.
134 lines
2.9 KiB
Go
134 lines
2.9 KiB
Go
package ebpf
|
|
|
|
import (
|
|
"fmt"
|
|
|
|
"github.com/cilium/ebpf/asm"
|
|
"github.com/cilium/ebpf/internal/btf"
|
|
)
|
|
|
|
// link resolves bpf-to-bpf calls.
|
|
//
|
|
// Each library may contain multiple functions / labels, and is only linked
|
|
// if prog references one of these functions.
|
|
//
|
|
// Libraries also linked.
|
|
func link(prog *ProgramSpec, libs []*ProgramSpec) error {
|
|
var (
|
|
linked = make(map[*ProgramSpec]bool)
|
|
pending = []asm.Instructions{prog.Instructions}
|
|
insns asm.Instructions
|
|
)
|
|
for len(pending) > 0 {
|
|
insns, pending = pending[0], pending[1:]
|
|
for _, lib := range libs {
|
|
if linked[lib] {
|
|
continue
|
|
}
|
|
|
|
needed, err := needSection(insns, lib.Instructions)
|
|
if err != nil {
|
|
return fmt.Errorf("linking %s: %w", lib.Name, err)
|
|
}
|
|
|
|
if !needed {
|
|
continue
|
|
}
|
|
|
|
linked[lib] = true
|
|
prog.Instructions = append(prog.Instructions, lib.Instructions...)
|
|
pending = append(pending, lib.Instructions)
|
|
|
|
if prog.BTF != nil && lib.BTF != nil {
|
|
if err := btf.ProgramAppend(prog.BTF, lib.BTF); err != nil {
|
|
return fmt.Errorf("linking BTF of %s: %w", lib.Name, err)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func needSection(insns, section asm.Instructions) (bool, error) {
|
|
// A map of symbols to the libraries which contain them.
|
|
symbols, err := section.SymbolOffsets()
|
|
if err != nil {
|
|
return false, err
|
|
}
|
|
|
|
for _, ins := range insns {
|
|
if ins.Reference == "" {
|
|
continue
|
|
}
|
|
|
|
if ins.OpCode.JumpOp() != asm.Call || ins.Src != asm.PseudoCall {
|
|
continue
|
|
}
|
|
|
|
if ins.Constant != -1 {
|
|
// This is already a valid call, no need to link again.
|
|
continue
|
|
}
|
|
|
|
if _, ok := symbols[ins.Reference]; !ok {
|
|
// Symbol isn't available in this section
|
|
continue
|
|
}
|
|
|
|
// At this point we know that at least one function in the
|
|
// library is called from insns, so we have to link it.
|
|
return true, nil
|
|
}
|
|
|
|
// None of the functions in the section are called.
|
|
return false, nil
|
|
}
|
|
|
|
func fixupJumpsAndCalls(insns asm.Instructions) error {
|
|
symbolOffsets := make(map[string]asm.RawInstructionOffset)
|
|
iter := insns.Iterate()
|
|
for iter.Next() {
|
|
ins := iter.Ins
|
|
|
|
if ins.Symbol == "" {
|
|
continue
|
|
}
|
|
|
|
if _, ok := symbolOffsets[ins.Symbol]; ok {
|
|
return fmt.Errorf("duplicate symbol %s", ins.Symbol)
|
|
}
|
|
|
|
symbolOffsets[ins.Symbol] = iter.Offset
|
|
}
|
|
|
|
iter = insns.Iterate()
|
|
for iter.Next() {
|
|
i := iter.Index
|
|
offset := iter.Offset
|
|
ins := iter.Ins
|
|
|
|
switch {
|
|
case ins.IsFunctionCall() && ins.Constant == -1:
|
|
// Rewrite bpf to bpf call
|
|
callOffset, ok := symbolOffsets[ins.Reference]
|
|
if !ok {
|
|
return fmt.Errorf("instruction %d: reference to missing symbol %q", i, ins.Reference)
|
|
}
|
|
|
|
ins.Constant = int64(callOffset - offset - 1)
|
|
|
|
case ins.OpCode.Class() == asm.JumpClass && ins.Offset == -1:
|
|
// Rewrite jump to label
|
|
jumpOffset, ok := symbolOffsets[ins.Reference]
|
|
if !ok {
|
|
return fmt.Errorf("instruction %d: reference to missing symbol %q", i, ins.Reference)
|
|
}
|
|
|
|
ins.Offset = int16(jumpOffset - offset - 1)
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|