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Date: Thu, 14 May 2009 22:45:27 -0300
From: Arnaldo Carvalho de Melo <acme@...hat.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...e.hu>, Clark Williams <williams@...hat.com>,
John Kacur <jkacur@...hat.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH] perf_counter: Allow specifying a pid to record
commit ee8ffeaf1ba6aee56cf822cba291fbacb5dd450b
Author: Arnaldo Carvalho de Melo <acme@...hat.com>
Date: Thu May 14 22:41:18 2009 -0300
perf_count: Allow connecting to an existing thread
Impact: new command line option
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 record' can get what
it needs.
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
diff --git a/Documentation/perf_counter/builtin-record.c b/Documentation/perf_counter/builtin-record.c
index 5f5e6df..fa57f4b 100644
--- a/Documentation/perf_counter/builtin-record.c
+++ b/Documentation/perf_counter/builtin-record.c
@@ -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;
@@ -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;
@@ -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"
);
@@ -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;
@@ -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;
@@ -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)
@@ -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++) {
@@ -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);
+ }
}
}
--
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