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perf record: Allow specifying a pid to record
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Allow specifying a pid instead of always fork+exec'ing a command.

Because the PERF_EVENT_COMM and PERF_EVENT_MMAP events happened before
we connected, we must synthesize them so that 'perf report' can get what
it needs.

[ Impact: add new command line option ]

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20090515015046.GA13664@ghostprotocols.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Arnaldo Carvalho de Melo authored and Ingo Molnar committed May 15, 2009
1 parent 5bb9efe commit 1a853e3
Showing 1 changed file with 146 additions and 17 deletions.
163 changes: 146 additions & 17 deletions Documentation/perf_counter/builtin-record.c
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,9 @@

#include "perf.h"

#define ALIGN(x,a) __ALIGN_MASK(x,(typeof(x))(a)-1)
#define __ALIGN_MASK(x,mask) (((x)+(mask))&~(mask))

static int nr_counters = 0;
static __u64 event_id[MAX_COUNTERS] = { };
static int default_interval = 100000;
Expand All @@ -47,6 +50,7 @@ static char *output_name = "output.perf";
static int group = 0;
static unsigned int realtime_prio = 0;
static int system_wide = 0;
static pid_t target_pid = -1;
static int inherit = 1;
static int nmi = 1;

Expand Down Expand Up @@ -180,6 +184,7 @@ static void display_help(void)
" -c CNT --count=CNT # event period to sample\n"
" -m pages --mmap_pages=<pages> # number of mmap data pages\n"
" -o file --output=<file> # output file\n"
" -p pid --pid=<pid> # record events on existing pid\n"
" -r prio --realtime=<prio> # use RT prio\n"
" -s --system # system wide profiling\n"
);
Expand All @@ -199,13 +204,14 @@ static void process_options(int argc, const char *argv[])
{"event", required_argument, NULL, 'e'},
{"mmap_pages", required_argument, NULL, 'm'},
{"output", required_argument, NULL, 'o'},
{"pid", required_argument, NULL, 'p'},
{"realtime", required_argument, NULL, 'r'},
{"system", no_argument, NULL, 's'},
{"inherit", no_argument, NULL, 'i'},
{"nmi", no_argument, NULL, 'n'},
{NULL, 0, NULL, 0 }
};
int c = getopt_long(argc, argv, "+:c:e:m:o:r:sin",
int c = getopt_long(argc, argv, "+:c:e:m:o:p:r:sin",
long_options, &option_index);
if (c == -1)
break;
Expand All @@ -215,6 +221,7 @@ static void process_options(int argc, const char *argv[])
case 'e': error = parse_events(optarg); break;
case 'm': mmap_pages = atoi(optarg); break;
case 'o': output_name = strdup(optarg); break;
case 'p': target_pid = atoi(optarg); break;
case 'r': realtime_prio = atoi(optarg); break;
case 's': system_wide ^= 1; break;
case 'i': inherit ^= 1; break;
Expand All @@ -223,7 +230,7 @@ static void process_options(int argc, const char *argv[])
}
}

if (argc - optind == 0)
if (argc - optind == 0 && target_pid == -1)
error = 1;

if (error)
Expand Down Expand Up @@ -350,15 +357,135 @@ static struct mmap_data mmap_array[MAX_NR_CPUS][MAX_COUNTERS];
static int nr_poll;
static int nr_cpu;

static void open_counters(int cpu)
struct mmap_event {
struct perf_event_header header;
__u32 pid, tid;
__u64 start;
__u64 len;
__u64 pgoff;
char filename[PATH_MAX];
};
struct comm_event {
struct perf_event_header header;
__u32 pid,tid;
char comm[16];
};

static pid_t pid_synthesize_comm_event(pid_t pid)
{
char filename[PATH_MAX];
char bf[BUFSIZ];
struct comm_event comm_ev;
size_t size;
int fd;

snprintf(filename, sizeof(filename), "/proc/%d/stat", pid);

fd = open(filename, O_RDONLY);
if (fd < 0) {
fprintf(stderr, "couldn't open %s\n", filename);
exit(EXIT_FAILURE);
}
if (read(fd, bf, sizeof(bf)) < 0) {
fprintf(stderr, "couldn't read %s\n", filename);
exit(EXIT_FAILURE);
}
close(fd);

pid_t spid, ppid;
char state;
char comm[18];

memset(&comm_ev, 0, sizeof(comm_ev));
int nr = sscanf(bf, "%d %s %c %d %d ",
&spid, comm, &state, &ppid, &comm_ev.pid);
if (nr != 5) {
fprintf(stderr, "couldn't get COMM and pgid, malformed %s\n",
filename);
exit(EXIT_FAILURE);
}
comm_ev.header.type = PERF_EVENT_COMM;
comm_ev.tid = pid;
size = strlen(comm);
comm[--size] = '\0'; /* Remove the ')' at the end */
--size; /* Remove the '(' at the begin */
memcpy(comm_ev.comm, comm + 1, size);
size = ALIGN(size, sizeof(uint64_t));
comm_ev.header.size = sizeof(comm_ev) - (sizeof(comm_ev.comm) - size);
int ret = write(output, &comm_ev, comm_ev.header.size);
if (ret < 0) {
perror("failed to write");
exit(-1);
}
return comm_ev.pid;
}

static void pid_synthesize_mmap_events(pid_t pid, pid_t pgid)
{
char filename[PATH_MAX];
FILE *fp;

snprintf(filename, sizeof(filename), "/proc/%d/maps", pid);

fp = fopen(filename, "r");
if (fp == NULL) {
fprintf(stderr, "couldn't open %s\n", filename);
exit(EXIT_FAILURE);
}
while (1) {
char bf[BUFSIZ];
unsigned char vm_read, vm_write, vm_exec, vm_mayshare;
struct mmap_event mmap_ev = {
.header.type = PERF_EVENT_MMAP,
};
unsigned long ino;
int major, minor;
size_t size;
if (fgets(bf, sizeof(bf), fp) == NULL)
break;

/* 00400000-0040c000 r-xp 00000000 fd:01 41038 /bin/cat */
sscanf(bf, "%llx-%llx %c%c%c%c %llx %x:%x %lu",
&mmap_ev.start, &mmap_ev.len,
&vm_read, &vm_write, &vm_exec, &vm_mayshare,
&mmap_ev.pgoff, &major, &minor, &ino);
if (vm_exec == 'x') {
char *execname = strrchr(bf, ' ');

if (execname == NULL || execname[1] != '/')
continue;

execname += 1;
size = strlen(execname);
execname[size - 1] = '\0'; /* Remove \n */
memcpy(mmap_ev.filename, execname, size);
size = ALIGN(size, sizeof(uint64_t));
mmap_ev.len -= mmap_ev.start;
mmap_ev.header.size = (sizeof(mmap_ev) -
(sizeof(mmap_ev.filename) - size));
mmap_ev.pid = pgid;
mmap_ev.tid = pid;

if (write(output, &mmap_ev, mmap_ev.header.size) < 0) {
perror("failed to write");
exit(-1);
}
}
}

fclose(fp);
}

static void open_counters(int cpu, pid_t pid)
{
struct perf_counter_hw_event hw_event;
int counter, group_fd;
int track = 1;
pid_t pid = -1;

if (cpu < 0)
pid = 0;
if (pid > 0) {
pid_t pgid = pid_synthesize_comm_event(pid);
pid_synthesize_mmap_events(pid, pgid);
}

group_fd = -1;
for (counter = 0; counter < nr_counters; counter++) {
Expand Down Expand Up @@ -435,22 +562,24 @@ int cmd_record(int argc, const char **argv)
argc -= optind;
argv += optind;

if (!system_wide)
open_counters(-1);
else for (i = 0; i < nr_cpus; i++)
open_counters(i);
if (!system_wide) {
open_counters(-1, target_pid != -1 ? target_pid : 0);
} else for (i = 0; i < nr_cpus; i++)
open_counters(i, target_pid);

signal(SIGCHLD, sig_handler);
signal(SIGINT, sig_handler);

pid = fork();
if (pid < 0)
perror("failed to fork");
if (target_pid == -1) {
pid = fork();
if (pid < 0)
perror("failed to fork");

if (!pid) {
if (execvp(argv[0], argv)) {
perror(argv[0]);
exit(-1);
if (!pid) {
if (execvp(argv[0], argv)) {
perror(argv[0]);
exit(-1);
}
}
}

Expand Down

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