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perf_linux.go
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perf_linux.go
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// Copyright 2016-2018 Authors of Cilium
//
// 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.
// +build linux
package bpf
/*
#cgo CFLAGS: -I../../bpf/include
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <linux/unistd.h>
#include <linux/bpf.h>
#include <linux/perf_event.h>
#include <sys/resource.h>
#include <stdlib.h>
#define READ_ONCE(x) (*(volatile typeof(x) *)&x)
#define WRITE_ONCE(x, v) (*(volatile typeof(x) *)&x) = (v)
// Contract with kernel/user space on perf ring buffer. From
// kernel/events/ring_buffer.c:
//
// kernel user
//
// if (LOAD ->data_tail) { LOAD ->data_head
// (A) smp_rmb() (C)
// STORE $data LOAD $data
// smp_wmb() (B) smp_mb() (D)
// STORE ->data_head STORE ->data_tail
// }
//
// Where A pairs with D, and B pairs with C.
//
// In our case (A) is a control dependency that separates the load
// of the ->data_tail and the stores of $data. In case ->data_tail
// indicates there is no room in the buffer to store $data we do
// not. D needs to be a full barrier since it separates the data
// READ from the tail WRITE. For B a WMB is sufficient since it
// separates two WRITEs, and for C an RMB is sufficient since it
// separates two READs.
#if defined(__x86_64__)
# define barrier() \
asm volatile("" ::: "memory")
# define smp_store_release(p, v) \
do { \
barrier(); \
WRITE_ONCE(*p, v); \
} while (0)
# define smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = READ_ONCE(*p); \
barrier(); \
___p1; \
})
static inline uint64_t perf_read_head(struct perf_event_mmap_page *up)
{
return smp_load_acquire(&up->data_head);
}
static inline void perf_write_tail(struct perf_event_mmap_page *up,
uint64_t data_tail)
{
smp_store_release(&up->data_tail, data_tail);
}
#else
# define smp_mb() __sync_synchronize()
# define smp_rmb() __sync_synchronize()
static inline uint64_t perf_read_head(struct perf_event_mmap_page *up)
{
uint64_t data_head = READ_ONCE(up->data_head);
smp_rmb();
return data_head;
}
static inline void perf_write_tail(struct perf_event_mmap_page *up,
uint64_t data_tail)
{
smp_mb();
WRITE_ONCE(up->data_tail, data_tail);
}
#endif
void create_perf_event_attr(int type, int config, int sample_type,
int wakeup_events, void *attr)
{
struct perf_event_attr *ptr = attr;
memset(ptr, 0, sizeof(*ptr));
ptr->type = type;
ptr->config = config;
ptr->sample_type = sample_type;
ptr->sample_period = 1;
ptr->wakeup_events = wakeup_events;
}
static void dump_data(uint8_t *data, size_t size, int cpu)
{
int i;
printf("event on cpu%d: ", cpu);
for (i = 0; i < size; i++)
printf("%02x ", data[i]);
printf("\n");
}
struct event_sample {
struct perf_event_header header;
uint32_t size;
uint8_t data[];
};
struct read_state {
void *base;
uint64_t raw_size;
uint64_t last_size;
};
void perf_event_reset_tail(void *_page)
{
struct perf_event_mmap_page *up = _page;
uint64_t data_head = perf_read_head(up);
// Reset tail to good known state aka tell kernel we've
// consumed all data.
perf_write_tail(up, data_head);
}
int perf_event_read_init(int page_count, int page_size, void *_page,
void *_state)
{
struct perf_event_mmap_page *up = _page;
struct read_state *state = _state;
uint64_t data_tail = up->data_tail;
if (perf_read_head(up) == data_tail)
return 0;
state->raw_size = page_count * page_size;
state->base = ((uint8_t *)up) + page_size;
state->last_size = 0;
return 1;
}
int perf_event_read(int page_size, void *_page, void *_state,
void *_buf, void *_msg, void *_sample, void *_lost)
{
struct perf_event_mmap_page *up = _page;
struct read_state *state = _state;
void **sample = (void **) _sample;
void **lost = (void **) _lost;
void **msg = (void **) _msg;
void **buf = (void **) _buf;
uint64_t e_size, data_tail;
struct event_sample *e;
int trunc = 0;
void *begin;
data_tail = up->data_tail + state->last_size;
perf_write_tail(up, data_tail);
if (perf_read_head(up) == data_tail)
return 0;
// raw_size is guaranteed power of 2
e = begin = state->base + (data_tail & (state->raw_size - 1));
e_size = state->last_size = e->header.size;
if (begin + e_size > state->base + state->raw_size) {
uint64_t len = state->base + state->raw_size - begin;
uint64_t len_first, len_secnd;
void *ptr = *buf;
// For small sizes, we just go with prealloc'ed buffer.
if (e_size > page_size) {
ptr = realloc(*buf, e_size);
if (!ptr) {
ptr = *buf;
trunc = 1;
} else {
*buf = ptr;
}
}
len_first = trunc ? (len <= page_size ? len : page_size) : len;
memcpy(ptr, begin, len_first);
len_secnd = trunc ? (page_size - len_first) : e_size - len;
memcpy(ptr + len_first, state->base, len_secnd);
e = ptr;
}
*msg = e;
if (e->header.type == PERF_RECORD_SAMPLE) {
*sample = e;
} else if (e->header.type == PERF_RECORD_LOST) {
*lost = e;
}
return 1 + trunc;
}
*/
import "C"
import (
"encoding/binary"
"fmt"
"io"
"os"
"path"
"reflect"
"runtime"
"time"
"unsafe"
"github.com/cilium/cilium/pkg/metrics"
"github.com/cilium/cilium/pkg/option"
"github.com/cilium/cilium/pkg/spanstat"
"golang.org/x/sys/unix"
)
const (
MAX_POLL_EVENTS = 32
)
type PerfEventConfig struct {
NumCpus int
NumPages int
MapName string
Type int
Config int
SampleType int
WakeupEvents int
}
func DefaultPerfEventConfig() *PerfEventConfig {
return &PerfEventConfig{
MapName: EventsMapName,
Type: PERF_TYPE_SOFTWARE,
Config: PERF_COUNT_SW_BPF_OUTPUT,
SampleType: PERF_SAMPLE_RAW,
WakeupEvents: 1,
NumCpus: runtime.NumCPU(),
NumPages: 8,
}
}
type PerfEvent struct {
cpu int
Fd int
pagesize int
npages int
lost uint64
trunc uint64
unknown uint64
data []byte
// state is placed here to reduce memory allocations
state unsafe.Pointer
// buf is placed here to reduce memory allocations
buf unsafe.Pointer
}
// PerfEventHeader must match 'struct perf_event_header in <linux/perf_event.h>.
type PerfEventHeader struct {
Type uint32
Misc uint16
TotalSize uint16
}
// PerfEventSample must match 'struct perf_event_sample in kernel sources.
type PerfEventSample struct {
PerfEventHeader
Size uint32
data byte // Size bytes of data
}
// PerfEventLost must match 'struct perf_event_lost in kernel sources.
type PerfEventLost struct {
PerfEventHeader
Id uint64
Lost uint64
}
func (e *PerfEventSample) DataDirect() []byte {
// http://stackoverflow.com/questions/27532523/how-to-convert-1024c-char-to-1024byte
return (*[1 << 30]byte)(unsafe.Pointer(&e.data))[:int(e.Size):int(e.Size)]
}
func (e *PerfEventSample) DataCopy() []byte {
return C.GoBytes(unsafe.Pointer(&e.data), C.int(e.Size))
}
type ReceiveFunc func(msg *PerfEventSample, cpu int)
type LostFunc func(msg *PerfEventLost, cpu int)
// ErrorFunc is run when reading PerfEvent results in an error
type ErrorFunc func(msg *PerfEvent)
func PerfEventOpen(config *PerfEventConfig, pid int, cpu int, groupFD int, flags int) (*PerfEvent, error) {
attr := C.struct_perf_event_attr{}
C.create_perf_event_attr(
C.int(config.Type),
C.int(config.Config),
C.int(config.SampleType),
C.int(config.WakeupEvents),
unsafe.Pointer(&attr),
)
var duration *spanstat.SpanStat
if option.Config.MetricsConfig.BPFSyscallDurationEnabled {
duration = spanstat.Start()
}
ret, _, err := unix.Syscall6(
unix.SYS_PERF_EVENT_OPEN,
uintptr(unsafe.Pointer(&attr)),
uintptr(pid),
uintptr(cpu),
uintptr(groupFD),
uintptr(flags), 0)
if option.Config.MetricsConfig.BPFSyscallDurationEnabled {
metrics.BPFSyscallDuration.WithLabelValues(metricOpPerfEventOpen, metrics.Errno2Outcome(err)).Observe(duration.EndError(err).Total().Seconds())
}
if int(ret) > 0 && err == 0 {
return &PerfEvent{
cpu: cpu,
Fd: int(ret),
}, nil
}
return nil, fmt.Errorf("Unable to open perf event: %s", err)
}
func (e *PerfEvent) Mmap(pagesize int, npages int) error {
datasize := uint32(pagesize) * uint32(npages)
if (datasize & (datasize - 1)) != 0 {
return fmt.Errorf("Unable to mmap perf event: ring size not power of 2")
}
size := pagesize * (npages + 1)
data, err := unix.Mmap(e.Fd,
0,
size,
unix.PROT_READ|unix.PROT_WRITE,
unix.MAP_SHARED)
if err != nil {
return fmt.Errorf("Unable to mmap perf event: %s", err)
}
e.pagesize = pagesize
e.npages = npages
e.data = data
return nil
}
func (e *PerfEvent) Munmap() error {
return unix.Munmap(e.data)
}
// allocateBuffers initializes the buffers for sharing between Golang and C.
func (e *PerfEvent) allocateBuffers() {
// C.malloc() will crash the program if allocation fails, skip check:
// https://golang.org/cmd/cgo/
e.state = C.malloc(C.size_t(unsafe.Sizeof(C.struct_read_state{})))
e.buf = C.malloc(C.size_t(e.pagesize))
}
func (e *PerfEvent) freeBuffers() {
C.free(e.buf)
C.free(e.state)
}
func (e *PerfEvent) Enable() error {
e.allocateBuffers()
var duration *spanstat.SpanStat
if option.Config.MetricsConfig.BPFSyscallDurationEnabled {
duration = spanstat.Start()
}
err := unix.IoctlSetInt(e.Fd, unix.PERF_EVENT_IOC_ENABLE, 0)
if option.Config.MetricsConfig.BPFSyscallDurationEnabled {
metrics.BPFSyscallDuration.WithLabelValues(metricOpPerfEventEnable, metrics.Error2Outcome(err)).Observe(duration.EndError(err).Total().Seconds())
}
if err != nil {
e.freeBuffers()
return fmt.Errorf("Unable to enable perf event: %v", err)
}
return nil
}
func (e *PerfEvent) Disable() error {
var ret error
if e == nil {
return nil
}
// Does not fail in perf's kernel-side ioctl handler, but even if
// there's not much we can do here ...
ret = nil
var duration *spanstat.SpanStat
if option.Config.MetricsConfig.BPFSyscallDurationEnabled {
duration = spanstat.Start()
}
err := unix.IoctlSetInt(e.Fd, unix.PERF_EVENT_IOC_DISABLE, 0)
if option.Config.MetricsConfig.BPFSyscallDurationEnabled {
metrics.BPFSyscallDuration.WithLabelValues(metricOpPerfEventDisable, metrics.Error2Outcome(err)).Observe(duration.EndError(err).Total().Seconds())
}
if err != nil {
ret = fmt.Errorf("Unable to disable perf event: %v", err)
}
e.freeBuffers()
return ret
}
// Read attempts to read all events from the perf event buffer, calling one of
// the receive / lost functions for each event. receiveFn is called when the
// event is a valid sample; lostFn is called when the kernel has attempted to
// write an event into the ringbuffer but ran out of space for the event.
//
// If all events are not read within a time period (default 20s), it will call
// errFn() and stop reading events.
func (e *PerfEvent) Read(receive ReceiveFunc, lostFn LostFunc, err ErrorFunc) {
// Prepare for reading and check if events are available
available := C.perf_event_read_init(C.int(e.npages), C.int(e.pagesize),
unsafe.Pointer(&e.data[0]), unsafe.Pointer(e.state))
// Poll false positive
if available == 0 {
return
}
timer := time.After(20 * time.Second)
read:
for {
var (
msg *PerfEventHeader
sample *PerfEventSample
lost *PerfEventLost
ok C.int
)
// Storing the C pointer to the temporary wrapper buffer on the
// stack allows CGo to understand it better when passing into
// perf_event_read(), to avoid the following error:
//
// runtime error: cgo argument has Go pointer to Go pointer
//
// We MUST store it back to 'e' in case it was reallocated.
wrapBuf := e.buf
if ok = C.perf_event_read(C.int(e.pagesize),
unsafe.Pointer(&e.data[0]), unsafe.Pointer(e.state),
unsafe.Pointer(&wrapBuf), unsafe.Pointer(&msg),
unsafe.Pointer(&sample), unsafe.Pointer(&lost)); ok == 0 {
e.buf = wrapBuf
break
}
e.buf = wrapBuf
if ok == 2 {
e.trunc++
}
if msg.Type == C.PERF_RECORD_SAMPLE {
receive(sample, e.cpu)
} else if msg.Type == C.PERF_RECORD_LOST {
e.lost += lost.Lost
if lostFn != nil {
lostFn(lost, e.cpu)
}
} else {
e.unknown++
}
select {
case <-timer:
err(e)
C.perf_event_reset_tail(unsafe.Pointer(&e.data[0]))
break read
default:
}
}
}
func (e *PerfEvent) Close() {
if e == nil {
return
}
unix.Close(e.Fd)
}
// Debug returns string with internal information about PerfEvent
func (e *PerfEvent) Debug() string {
return fmt.Sprintf("cpu: %d, Fd: %d, pagesize: %d, npages: %d, lost: %d, unknown: %d, state: %v", e.cpu, e.Fd, e.pagesize, e.npages, e.lost, e.unknown, C.GoBytes(e.state, C.sizeof_struct_read_state))
}
func (e *PerfEvent) DebugDump() string {
return fmt.Sprintf("%s, data: %v", e.Debug(), e.data)
}
type EPoll struct {
fd int
nfds int
events [MAX_POLL_EVENTS]unix.EpollEvent
}
func (ep *EPoll) AddFD(fd int, events uint32) error {
ev := unix.EpollEvent{
Events: events,
Fd: int32(fd),
}
return unix.EpollCtl(ep.fd, unix.EPOLL_CTL_ADD, fd, &ev)
}
func (ep *EPoll) Poll(timeout int) (int, error) {
nfds, err := unix.EpollWait(ep.fd, ep.events[0:], timeout)
if err != nil {
return 0, err
}
ep.nfds = nfds
return nfds, nil
}
func (ep *EPoll) Close() {
if ep.fd > 0 {
unix.Close(ep.fd)
}
}
type EventMap struct {
fd int
}
func openMap(path string) (*EventMap, error) {
fd, err := ObjGet(path)
if err != nil {
return nil, err
}
return &EventMap{
fd: fd,
}, nil
}
func (e *EventMap) Update(fd int, ubaPtr, sizeOf uintptr) error {
return UpdateElementFromPointers(e.fd, ubaPtr, sizeOf)
}
func (e *EventMap) Close() {
if e == nil {
return
}
unix.Close(e.fd)
}
type PerCpuEvents struct {
Cpus int
Npages int
Pagesize int
eventMap *EventMap
event map[int]*PerfEvent
poll EPoll
}
func NewPerCpuEvents(config *PerfEventConfig) (*PerCpuEvents, error) {
var err error
e := &PerCpuEvents{
Cpus: config.NumCpus,
Npages: config.NumPages,
Pagesize: os.Getpagesize(),
event: make(map[int]*PerfEvent),
}
defer func() {
if err != nil {
e.CloseAll()
}
}()
e.poll.fd, err = unix.EpollCreate1(0)
if err != nil {
return nil, err
}
mapPath := config.MapName
if !path.IsAbs(mapPath) {
mapPath = MapPath(mapPath)
}
e.eventMap, err = openMap(mapPath)
if err != nil {
return nil, err
}
for cpu := int(0); cpu < e.Cpus; cpu++ {
event, err := PerfEventOpen(config, -1, cpu, -1, 0)
if err != nil {
return nil, err
}
e.event[event.Fd] = event
if err = e.poll.AddFD(event.Fd, unix.EPOLLIN); err != nil {
return nil, err
}
if err = event.Mmap(e.Pagesize, e.Npages); err != nil {
return nil, err
}
if err = event.Enable(); err != nil {
return nil, err
}
}
uba := bpfAttrMapOpElem{
mapFd: uint32(e.eventMap.fd),
flags: uint64(0),
}
ubaPtr := uintptr(unsafe.Pointer(&uba))
ubaSizeOf := unsafe.Sizeof(uba)
for _, event := range e.event {
// FIXME: Not sure what to do here, the map has already been updated and we can't
// fully restore it.
uba.key = uint64(uintptr(unsafe.Pointer(&event.cpu)))
uba.value = uint64(uintptr(unsafe.Pointer(&event.Fd)))
if err := e.eventMap.Update(e.eventMap.fd, ubaPtr, ubaSizeOf); err != nil {
return nil, err
}
}
return e, nil
}
func (e *PerCpuEvents) Poll(timeout int) (int, error) {
return e.poll.Poll(timeout)
}
// ReadAll reads perf events
func (e *PerCpuEvents) ReadAll(receive ReceiveFunc, lost LostFunc, handleError ErrorFunc) error {
for i := 0; i < e.poll.nfds; i++ {
fd := int(e.poll.events[i].Fd)
if event, ok := e.event[fd]; ok {
event.Read(receive, lost, handleError)
}
}
return nil
}
func (e *PerCpuEvents) Stats() (uint64, uint64, uint64) {
var lost, trunc, unknown uint64
for _, event := range e.event {
lost += event.lost
trunc += event.trunc
unknown += event.unknown
}
return lost, trunc, unknown
}
func (e *PerCpuEvents) CloseAll() error {
var retErr error
e.eventMap.Close()
e.poll.Close()
for _, event := range e.event {
if err := event.Disable(); err != nil {
retErr = err
}
event.Munmap()
event.Close()
}
return retErr
}
// decode uses reflection to read bytes directly from 'reader' into the object
// pointed to from 'i'. Assumes that 'i' is a pointer.
//
// This function should not be used from performance-sensitive code.
func decode(i interface{}, reader io.ReadSeeker) error {
value := reflect.ValueOf(i).Elem()
decodeSize := int64(reflect.TypeOf(value).Size())
if _, err := reader.Seek(decodeSize, io.SeekStart); err != nil {
return fmt.Errorf("failed to seek into reader %d bytes", decodeSize)
}
_, _ = reader.Seek(0, io.SeekStart)
for i := 0; i < value.NumField(); i++ {
if err := binary.Read(reader, binary.LittleEndian, value.Field(i).Addr().Interface()); err != nil {
return fmt.Errorf("failed to decode field %d", i)
}
}
return nil
}
// ReadState is a golang reflection of C.struct_read_state{}
type ReadState struct {
Base uint64 // Actually a pointer
RawSize uint64
LastSize uint64
}
// Decode populates 'r' based on the bytes read from the specified reader.
//
// This function should not be used from performance-sensitive code.
func (r *ReadState) Decode(reader io.ReadSeeker) error {
return decode(r, reader)
}
// PerfEventMmapPage reflects the Linux 'struct perf_event_mmap_page'
type PerfEventMmapPage struct {
Version uint32 // version number of this structure
CompatVersion uint32 // lowest version this is compat with
Lock uint32 // seqlock for synchronization
Index uint32 // hardware event identifier
Offset int64 // add to hardware event value
TimeEnabled uint64 // time event active
TimeRunning uint64 // time event on cpu
//union {
Capabilities uint64
//struct {
// __u64 cap_bit0 : 1, /* Always 0, deprecated, see commit 860f085b74e9 */
// cap_bit0_is_deprecated : 1, /* Always 1, signals that bit 0 is zero */
// cap_user_rdpmc : 1, /* The RDPMC instruction can be used to read counts */
// cap_user_time : 1, /* The time_* fields are used */
// cap_user_time_zero : 1, /* The time_zero field is used */
// cap_____res : 59;
//};
//};
PmcWidth uint16
TimeShift uint16
TimeMult uint32
TimeOffset uint64
TimeZero uint64
Size uint32
Reserved [118*8 + 4]uint8 // align to 1k.
DataHead uint64 // head in the data section
DataTail uint64 // user-space written tail
DataOffset uint64 // where the buffer starts
DataSize uint64 // data buffer size
AuxHead uint64
AuxTail uint64
AuxOffset uint64
AuxSize uint64
}
// Decode populates 'p' base on the bytes read from the specified reader.
//
// This function should not be used from performance-sensitive code.
func (p *PerfEventMmapPage) Decode(reader io.ReadSeeker) error {
return decode(p, reader)
}
// PerfEventFromMemory creates an in-memory PerfEvent object for testing
// and analysis purposes. No kernel interaction is made.
//
// The caller MUST eventually call Disable() to free event resources.
func PerfEventFromMemory(page *PerfEventMmapPage, buf []byte) *PerfEvent {
pagesize := os.Getpagesize()
e := &PerfEvent{
cpu: 1,
pagesize: pagesize,
npages: int(page.DataSize) / pagesize,
data: buf,
}
e.allocateBuffers()
return e
}