https://sourceware.org/bugzilla/show_bug.cgi?id=30575
Bug ID: 30575
Summary: gprofng cannot profile application with clone3()
Product: binutils
Version: unspecified
Status: NEW
Severity: minor
Priority: P2
Component: gprofng
Assignee: vladimir.mezentsev at oracle dot com
Reporter: vladimir.mezentsev at oracle dot com
Target Milestone: ---
% cat clone.c
#define _GNU_SOURCE
#include <linux/sched.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <sys/syscall.h>
#include <stdlib.h>
#include <errno.h>
#include <stdint.h>
#include <sys/wait.h>
#include <time.h>
#ifndef __NR_clone3
#define __NR_clone3 -1
#endif
static pid_t sys_clone3(struct clone_args *args)
{
return syscall(__NR_clone3, args, sizeof(struct clone_args));
}
#define ptr_to_u64(ptr) ((unsigned long)((uintptr_t)(ptr)))
time_t
gethrtime (void)
{
struct timespec tp;
time_t rc = 0;
#ifdef CLOCK_MONOTONIC_RAW
int r = clock_gettime (CLOCK_MONOTONIC_RAW, &tp);
#else
int r = clock_gettime (CLOCK_MONOTONIC, &tp);
#endif
if (r == 0)
rc = ((time_t) tp.tv_sec) * 1e9 + (time_t) tp.tv_nsec;
return rc;
}
volatile long ax; /* temp variable for long calculation */
static void aaa()
{
long long count = 0;
time_t start = gethrtime ();
do {
ax = 0;
for (int j = 0; j < 1000000; j++)
ax = ax + 1;
count++;
}
while (start + 1e9 > gethrtime ());
char buf[256];
snprintf(buf, sizeof (buf),
"aaa(): Child process with pid: %lld count=%lld ax=%lld\n",
(long long) getpid(), count, ax);
write(1, buf, strlen(buf));
}
volatile long bx; /* temp variable for long calculation */
static void bbb()
{
long long count = 0;
time_t start = gethrtime ();
do {
bx = 0;
for (int j = 0; j < 1000000; j++)
bx = bx + 1;
count++;
}
while (start + 1e9 > gethrtime ());
char buf[256];
snprintf(buf, sizeof (buf),
"bbb(): Parent process with pid: %lld count=%lld bx=%lld\n",
(long long) getpid(), count, bx);
write(1, buf, strlen(buf));
}
int
main (int argc, char **argv)
{
int pidfd = -1;
pid_t parent_tid = -1, pid = -1;
struct clone_args args;
memset(&args, 0, sizeof(args));
args.parent_tid = ptr_to_u64(&parent_tid); /* CLONE_PARENT_SETTID */
args.pidfd = ptr_to_u64(&pidfd); /* CLONE_PIDFD */
args.flags = CLONE_PIDFD | CLONE_PARENT_SETTID;
args.exit_signal = SIGCHLD;
pid = sys_clone3(&args);
// pid = clone3(&args, sizeof(args));
if (pid < 0) {
fprintf(stderr, "%s - Failed to create new process\n", strerror(errno));
exit(EXIT_FAILURE);
}
if (pid == 0) {
printf("Child process with pid %d\n", getpid());
aaa();
exit(EXIT_SUCCESS);
}
bbb();
printf("Parent process received child's pid %d as return value\n", pid);
printf("Parent process received child's pidfd %d\n", *(int *)args.pidfd);
printf("Parent process received child's pid %d as return argument\n",
*(pid_t *)args.parent_tid);
if (waitid(P_ALL, pid, NULL, 0) == 0) {
fprintf(stderr, "Managed to wait on CLONE_NO_WAITALL process with
waitid(P_ALL)\n");
}
return 0;
}
% gcc clone3.c
% gprofng collect app -O t.er ./a.out
Creating experiment directory t.er (Process ID: 535114) ...
Child process with pid 535117
bbb(): Parent process with pid: 535114 count=331 bx=1000000
Parent process received child's pid 535117 as return value
Parent process received child's pidfd 3
Parent process received child's pid 535117 as return argument
aaa(): Child process with pid: 535117 count=336 ax=1000000
aaa is not in the function list:
% gprofng display text -func t.er/
Functions sorted by metric: Exclusive Total CPU Time
Excl. Total Incl. Total Name
CPU CPU
sec. % sec. %
0.650 100.00 0.650 100.00 <Total>
0.650 100.00 0.650 100.00 bbb
0. 0. 0.650 100.00 __libc_start_call_main
0. 0. 0.650 100.00 main
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