/*
* smpl_pebs.c - PEBS standalone (no libpfm) sampling example for P4/Xeon
* (support 32-bit and 64-bit modes)
*
* Copyright (c) 2005-2006 Hewlett-Packard Development Company, L.P.
* Contributed by Stephane Eranian <eranian@hpl.hp.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
* of the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
* OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* This file is part of libpfm, a performance monitoring support library for
* applications on Linux.
*/
#ifndef _GNU_SOURCE
#define _GNU_SOURCE /* for getline */
#endif
#include <sys/types.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <syscall.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/ptrace.h>
#include <sys/mman.h>
#include <perfmon/perfmon.h>
#include <perfmon/perfmon_pebs_p4_smpl.h>
#define NUM_PMCS 32
#define NUM_PMDS 32
#define SMPL_PERIOD 100000ULL /* must not use more bits than actual HW counter width */
typedef pfm_pebs_p4_smpl_hdr_t smpl_hdr_t;
typedef pfm_pebs_p4_smpl_entry_t smpl_entry_t;
typedef pfm_pebs_p4_smpl_arg_t smpl_arg_t;
#define FMT_NAME PFM_PEBS_P4_SMPL_NAME
static uint64_t collected_samples;
static void fatal_error(char *fmt,...) __attribute__((noreturn));
static void
fatal_error(char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
exit(1);
}
static void
warning(char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
}
int
child(char **arg)
{
/*
* force the task to stop before executing the first
* user level instruction
*/
ptrace(PTRACE_TRACEME, 0, NULL, NULL);
execvp(arg[0], arg);
/* not reached */
exit(1);
}
static void
process_smpl_buf(smpl_hdr_t *hdr)
{
static uint64_t last_overflow = ~0; /* initialize to biggest value possible */
static uint64_t last_count;
smpl_entry_t *ent;
unsigned long count;
uint64_t entry;
count = (hdr->ds.pebs_index - hdr->ds.pebs_buf_base)/sizeof(*ent);
if (hdr->overflows == last_overflow && last_count == count) {
warning("skipping identical set of samples %"PRIu64" = %"PRIu64"\n",
hdr->overflows, last_overflow);
return;
}
last_count = count;
last_overflow = hdr->overflows;
/*
* the beginning of the buffer does not necessarily follow the header
* due to alignement.
*/
ent = (smpl_entry_t *)((unsigned long)(hdr+1)+ hdr->start_offs);
entry = collected_samples;
while(count--) {
printf("entry %06"PRIu64" eflags:0x%08lx EAX:0x%08lx ESP:0x%08lx IP:0x%08lx\n",
entry,
ent->eflags,
ent->eax,
ent->esp,
ent->ip);
ent++;
entry++;
}
collected_samples = entry;
}
static int
get_cpuinfo_attr(char *attr, char *ret_buf, size_t maxlen)
{
FILE *fp;
int ret = -1;
size_t attr_len, buf_len = 0;
char *p, *value = NULL;
char *buffer = NULL;
if (attr == NULL || ret_buf == NULL || maxlen < 1)
return -1;
attr_len = strlen(attr);
fp = fopen("/proc/cpuinfo", "r");
if (fp == NULL)
return -1;
while(getline(&buffer, &buf_len, fp) != -1){
/* skip blank lines */
if (*buffer == '\n')
continue;
p = strchr(buffer, ':');
if (p == NULL)
goto error;
/*
* p+2: +1 = space, +2= firt character
* strlen()-1 gets rid of \n
*/
*p = '\0';
value = p+2;
value[strlen(value)-1] = '\0';
if (!strncmp(attr, buffer, attr_len))
break;
}
strncpy(ret_buf, value, maxlen-1);
ret_buf[maxlen-1] = '\0';
ret = 0;
error:
free(buffer);
fclose(fp);
return ret;
}
static void
check_valid_cpu(void)
{
int ret, siblings, family, cores;
char buffer[128];
ret = get_cpuinfo_attr("vendor_id", buffer, sizeof(buffer));
if (ret == -1 || strcmp(buffer, "GenuineIntel"))
fatal_error("this programs works only with Intel processors\n");
ret = get_cpuinfo_attr("cpu family", buffer, sizeof(buffer));
if (ret == -1)
fatal_error("cannot determine processor family\n");
family = atoi(buffer);
if (family != 15)
fatal_error("this program only works for P4/Xeon with PEBS (found family=%d)\n", family);
ret = get_cpuinfo_attr("siblings", buffer, sizeof(buffer));
if (ret == -1)
fatal_error("cannot deterimine number of siblings\n");
siblings = atoi(buffer);
ret = get_cpuinfo_attr("cpu cores", buffer, sizeof(buffer));
if (ret == -1)
fatal_error("cannot determine number of cpu cores\n");
cores = atoi(buffer);
if (siblings > cores)
fatal_error("PEBS does not work when HyperThreading is enabled\n");
}
int
main(int argc, char **argv)
{
pfarg_pmr_t pd[NUM_PMDS];
pfarg_pmr_t pc[NUM_PMCS];
smpl_arg_t buf_arg;
pfarg_msg_t msg;
smpl_hdr_t *hdr;
void *buf_addr;
pid_t pid;
int ret, fd, status, npmcs = 0;
check_valid_cpu();
if (argc < 2)
fatal_error("you need to pass a program to sample\n");
memset(pd, 0, sizeof(pd));
memset(pc, 0, sizeof(pc));
memset(&buf_arg, 0, sizeof(buf_arg));
buf_arg.buf_size = getpagesize();
buf_arg.cnt_reset = -SMPL_PERIOD;
/*
* trigger interrupt when reached 90% of buffer
*/
buf_arg.intr_thres = (buf_arg.buf_size/sizeof(smpl_entry_t))*90/100;
fd = pfm_create(PFM_FL_SMPL_FMT, NULL, FMT_NAME, &buf_arg, sizeof(buf_arg));
if (fd == -1) {
if (errno == ENOSYS) {
fatal_error("Your kernel does not have performance monitoring support!\n");
}
fatal_error("cannot create session %s, maybe you do not have the P4/Xeon PEBS sampling format in the kernel.\n Check /sys/kernel/perfmon\n", strerror(errno));
}
/*
* retrieve the virtual address at which the sampling
* buffer has been mapped
*/
buf_addr = mmap(NULL, (size_t)buf_arg.buf_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (buf_addr == MAP_FAILED)
fatal_error("cannot mmap sampling buffer errno %d\n", errno);
printf("session [%d] buffer mapped @%p\n", fd, buf_addr);
hdr = (smpl_hdr_t *)buf_addr;
printf("pebs_base=0x%lx pebs_end=0x%lx index=0x%lx\n"
"intr=0x%lx version=%u.%u\n"
"entry_size=%zu ds_size=%zu\n",
hdr->ds.pebs_buf_base,
hdr->ds.pebs_abs_max,
hdr->ds.pebs_index,
hdr->ds.pebs_intr_thres,
PFM_VERSION_MAJOR(hdr->version),
PFM_VERSION_MINOR(hdr->version),
sizeof(smpl_entry_t),
sizeof(hdr->ds));
if (PFM_VERSION_MAJOR(hdr->version) < 1)
fatal_error("invalid buffer format version\n");
/*
* using the replay_event event
*
* CRU_ESCR2.usr=1
* CRU_ESCR2.event_mask=1 (NBOGUS)
* CRU_ESCR2.event_select=0x9 (replay_event)
*/
pc[npmcs].reg_num = 21;
pc[npmcs].reg_value = (9ULL <<25) | (1ULL<<9) |(1ULL<<2);
npmcs++;
/*
* for PEBS, must use IQ_CCCR4 for thread0
* IQ_CCCR4.escr_select = 5
* IQ_CCCR4.enable= 1
* IQ_CCCR4.active_thread= 3
*
* We must disable 64-bit emulation by the kernel
* on the associated counter when using PEBS. Otherwise
* we received a spurious interrupt for every counter overflow.
*/
pc[npmcs].reg_num = 31;
pc[npmcs].reg_flags = PFM_REGFL_NO_EMUL64;
pc[npmcs].reg_value = (5ULL << 13) | (1ULL<<12) | (3ULL<<16);
npmcs++;
/*
* PEBS_MATRIX_VERT.bit0=1 (1st level cache load miss retired)
*/
pc[npmcs].reg_num = 63;
pc[npmcs].reg_value = 1;
npmcs++;
/*
* PEBS_ENABLE.enable=1 (bit0)
* PEBS_ENABLE.uops=1 (bit 24)
* PEBS_ENABLE.my_thr=1 (bit 25)
*/
pc[npmcs].reg_num = 64;
pc[npmcs].reg_value = (1ULL<<25)|(1ULL<<24) | 1ULL;
npmcs++;
/*
* Must use IQ_CCCR4/IQ_CTR4 with PEBS for thread0
*
* IMPORTANT:
* SMPL_PERIOD MUST not exceed width of HW counter
* because no 64-bit virtualization is done by the
* kernel.
*/
pd[0].reg_num = 8;
pd[0].reg_flags = PFM_REGFL_OVFL_NOTIFY;
pd[0].reg_value = -SMPL_PERIOD;
/*
* Now program the registers
*/
if (pfm_write(fd, 0, PFM_RW_PMC, pc, npmcs * sizeof(*pc)) == -1)
fatal_error("pfm_writeerror errno %d\n",errno);
if (pfm_write(fd, 0, PFM_RW_PMD_ATTR, pd, sizeof(*pd)) == -1)
fatal_error("pfm_write(PMD) error errno %d\n",errno);
signal(SIGCHLD, SIG_IGN);
/*
* Create the child task
*/
if ((pid=fork()) == -1) fatal_error("Cannot fork process\n");
/*
* In order to get the PFM_END_MSG message, it is important
* to ensure that the child task does not inherit the file
* descriptor of the session. By default, file descriptor
* are inherited during exec(). We explicitely close it
* here. We could have set it up through fcntl(FD_CLOEXEC)
* to achieve the same thing.
*/
if (pid == 0) {
close(fd);
child(argv+1);
}
/*
* wait for the child to exec
*/
waitpid(pid, &status, WUNTRACED);
/*
* process is stopped at this point
*/
if (WIFEXITED(status)) {
warning("task %s [%d] exited already status %d\n", argv[1], pid, WEXITSTATUS(status));
goto terminate_session;
}
/*
* attach the session
*/
if (pfm_attach(fd, 0, pid) == -1)
fatal_error("pfm_attach error errno %d\n",errno);
/*
* start monitoring
*/
if (pfm_set_state(fd, 0, PFM_ST_START) == -1)
fatal_error("pfm_set_state(start) error errno %d\n",errno);
/*
* detach child. Side effect includes
* activation of monitoring.
*/
ptrace(PTRACE_DETACH, pid, NULL, 0);
/*
* core loop
*/
for(;;) {
/*
* wait for overflow/end notification messages
*/
ret = read(fd, &msg, sizeof(msg));
if (ret == -1) {
if(ret == -1 && errno == EINTR) {
warning("read interrupted, retrying\n");
continue;
}
fatal_error("cannot read perfmon msg: %s\n", strerror(errno));
}
switch(msg.type) {
case PFM_MSG_OVFL: /* the sampling buffer is full */
process_smpl_buf(hdr);
/*
* reactivate monitoring once we are done with the samples
*
* Note that this call can fail with EBUSY in non-blocking mode
* as the task may have disappeared while we were processing
* the samples.
*/
if (pfm_set_state(fd, 0, PFM_ST_RESTART) == -1) {
if (errno != EBUSY)
fatal_error("pfm_set_state(restart)_ error errno %d\n",errno);
else
warning("pfm_set_state(restart): task has probably terminated \n");
}
break;
case PFM_MSG_END: /* monitored task terminated */
warning("task terminated\n");
goto terminate_session;
default: fatal_error("unknown message type %d\n", msg.type);
}
}
terminate_session:
/*
* cleanup child
*/
wait4(pid, &status, 0, NULL);
/*
* check for any leftover samples
*/
process_smpl_buf(hdr);
munmap(buf_addr, (size_t)buf_arg.buf_size);
close(fd);
return 0;
}