/*
* smpl_core_pebs_sys.c - Intel Core processor PEBS system-wide example
*
* Copyright (c) 2008 Google, Inc
* Contributed by Stephane Eranian <eranian@gmail.com>
*
* Based on code:
* Copyright (c) 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.
*/
#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 <poll.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <perfmon/perfmon.h>
#include <perfmon/perfmon_pebs_core_smpl.h>
#include <perfmon/pfmlib.h>
#include <perfmon/pfmlib_core.h>
#include <perfmon/pfmlib_intel_atom.h>
#include "../detect_pmcs.h"
#define SMPL_EVENT "INSTRUCTIONS_RETIRED" /* not all event support PEBS */
#define NUM_PMCS 16
#define NUM_PMDS 16
#define SMPL_PERIOD 100000ULL /* must not use more bits than actual HW counter width */
typedef pfm_pebs_core_smpl_hdr_t smpl_hdr_t;
typedef pfm_pebs_core_smpl_entry_t smpl_entry_t;
typedef pfm_pebs_core_smpl_arg_t smpl_arg_t;
#define FMT_NAME PFM_PEBS_CORE_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
*/
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;
uint64_t entry;
unsigned long count;
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--) {
/*
* print some of the machine registers of each sample
*/
printf("entry %06"PRIu64" eflags:0x%08llx EAX:0x%08llx ESP:0x%08llx IP:0x%08llx\n",
entry,
(unsigned long long)ent->eflags,
(unsigned long long)ent->eax,
(unsigned long long)ent->esp,
(unsigned long long)ent->ip);
ent++;
entry++;
}
collected_samples = entry;
}
/*
* pin task to CPU
*/
#ifndef __NR_sched_setaffinity
#error "you need to define __NR_sched_setaffinity"
#endif
#define MAX_CPUS 2048
#define NR_CPU_BITS (MAX_CPUS>>3)
int
pin_cpu(pid_t pid, unsigned int cpu)
{
uint64_t my_mask[NR_CPU_BITS];
if (cpu >= MAX_CPUS)
fatal_error("this program supports only up to %d CPUs\n", MAX_CPUS);
my_mask[cpu>>6] = 1ULL << (cpu&63);
return syscall(__NR_sched_setaffinity, pid, sizeof(my_mask), &my_mask);
}
static volatile int done;
static void handler(int n)
{
done = 1;
}
int
main(int argc, char **argv)
{
pfmlib_input_param_t inp;
pfmlib_output_param_t outp;
pfmlib_core_input_param_t mod_inp;
pfmlib_options_t pfmlib_options;
pfarg_pmr_t pc[NUM_PMCS];
pfarg_pmd_attr_t pd[NUM_PMDS];
pfarg_sinfo_t sif;
struct pollfd fds;
smpl_arg_t buf_arg;
pfarg_msg_t msg;
smpl_hdr_t *hdr;
void *buf_addr;
uint64_t pebs_size;
pid_t pid;
int ret, fd, type;
unsigned int i;
uint32_t ctx_flags;
if (argc < 2)
fatal_error("you need to pass a program to sample\n");
if (pfm_initialize() != PFMLIB_SUCCESS)
fatal_error("libpfm intialization failed\n");
/*
* check we are on an Intel Core PMU
*/
pfm_get_pmu_type(&type);
if (type != PFMLIB_INTEL_CORE_PMU && type != PFMLIB_INTEL_ATOM_PMU)
fatal_error("This program only works with an Intel Core processor\n");
/*
* pass options to library (optional)
*/
memset(&pfmlib_options, 0, sizeof(pfmlib_options));
pfmlib_options.pfm_debug = 0; /* set to 1 for debug */
pfmlib_options.pfm_verbose = 1; /* set to 1 for verbose */
pfm_set_options(&pfmlib_options);
memset(pd, 0, sizeof(pd));
memset(pc, 0, sizeof(pc));
memset(&inp, 0, sizeof(inp));
memset(&outp, 0, sizeof(outp));
memset(&mod_inp, 0, sizeof(mod_inp));
memset(&sif, 0, sizeof(sif));
memset(&buf_arg, 0, sizeof(buf_arg));
memset(&fds, 0, sizeof(fds));
/*
* search for our sampling event
*/
if (pfm_find_full_event(SMPL_EVENT, &inp.pfp_events[0]) != PFMLIB_SUCCESS)
fatal_error("cannot find sampling event %s\n", SMPL_EVENT);
inp.pfp_event_count = 1;
inp.pfp_dfl_plm = PFM_PLM3;
/*
* important: inform libpfm we do use PEBS
*/
mod_inp.pfp_core_pebs.pebs_used = 1;
/*
* sampling buffer parameters
*/
pebs_size = 3 * getpagesize();
buf_arg.buf_size = pebs_size;
/*
* sampling period cannot use more bits than HW counter can supoprt
*/
buf_arg.cnt_reset = -SMPL_PERIOD;
/*
* We want a system-wide context for sampling
*/
ctx_flags = PFM_FL_SYSTEM_WIDE | PFM_FL_SMPL_FMT;
/*
* trigger notification (interrupt) when reaching the very end of
* the buffer
*/
buf_arg.intr_thres = (pebs_size/sizeof(smpl_entry_t))*90/100;
/*
* we want to measure CPU0, thus we pin ourself to the CPU before invoking
* perfmon. This ensures that the sampling buffer will be allocated on the
* same NUMA node.
*/
ret = pin_cpu(getpid(), 0);
if (ret)
fatal_error("cannot pin on CPU0");
/*
* create session and sampling buffer
*/
fd = pfm_create(ctx_flags, &sif, 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 PEBS sampling format in the kernel.\nCheck /sys/kernel/perfmon/formats\n", strerror(errno));
}
/*
* map buffer into our address space
*/
buf_addr = mmap(NULL, (size_t)buf_arg.buf_size, PROT_READ, MAP_PRIVATE, fd, 0);
printf("session [%d] buffer mapped @%p\n", fd, buf_addr);
if (buf_addr == MAP_FAILED)
fatal_error("cannot mmap sampling buffer errno %d\n", errno);
hdr = (smpl_hdr_t *)buf_addr;
printf("pebs_base=0x%llx pebs_end=0x%llx index=0x%llx\n"
"intr=0x%llx version=%u.%u\n"
"entry_size=%zu ds_size=%zu\n",
(unsigned long long)hdr->ds.pebs_buf_base,
(unsigned long long)hdr->ds.pebs_abs_max,
(unsigned long long)hdr->ds.pebs_index,
(unsigned long long)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");
/*
* get which PMC registers are available
*/
detect_unavail_pmu_regs(&sif, &inp.pfp_unavail_pmcs, NULL);
/*
* let libpfm figure out how to assign event onto PMU registers
*/
if (pfm_dispatch_events(&inp, &mod_inp, &outp, NULL) != PFMLIB_SUCCESS)
fatal_error("cannot assign event %s\n", SMPL_EVENT);
/*
* propagate PMC setup from libpfm to perfmon
*/
for (i=0; i < outp.pfp_pmc_count; i++) {
pc[i].reg_num = outp.pfp_pmcs[i].reg_num;
pc[i].reg_value = outp.pfp_pmcs[i].reg_value;
/*
* must disable 64-bit emulation on the PMC0 counter.
* PMC0 is the only counter useable with PEBS. We must disable
* 64-bit emulation to avoid getting interrupts for each
* sampling period, PEBS takes care of this part.
*/
if (pc[i].reg_num == 0)
pc[i].reg_flags = PFM_REGFL_NO_EMUL64;
}
/*
* propagate PMD set from libpfm to perfmon
*/
for (i=0; i < outp.pfp_pmd_count; i++)
pd[i].reg_num = outp.pfp_pmds[i].reg_num;
/*
* setup sampling period for first counter
* we want notification on overflow, i.e., when buffer is full
*/
pd[0].reg_flags = PFM_REGFL_OVFL_NOTIFY;
pd[0].reg_value = -SMPL_PERIOD;
pd[0].reg_long_reset = -SMPL_PERIOD;
pd[0].reg_short_reset = -SMPL_PERIOD;
/*
* Now program the registers
*/
if (pfm_write(fd, 0, PFM_RW_PMC, pc, outp.pfp_pmc_count * sizeof(*pc)) == -1)
fatal_error("pfm_write error errno %d\n",errno);
if (pfm_write(fd, 0, PFM_RW_PMD_ATTR, pd, outp.pfp_pmd_count * sizeof(*pd)) == -1)
fatal_error("pfm_write(PMD) error errno %d\n",errno);
/*
* attach the session to CPU0
*/
if (pfm_attach(fd, 0, 0) == -1)
fatal_error("pfm_attach error errno %d\n",errno);
/*
* Create the child task
*/
signal(SIGCHLD, handler);
if ((pid=fork()) == -1)
fatal_error("Cannot fork process\n");
if (pid == 0) {
/* child does not inherit context file descriptor */
close(fd);
/* if child is too short-lived we may not measure it */
child(argv+1);
}
/*
* start monitoring
*/
if (pfm_set_state(fd, 0, PFM_ST_START) == -1)
fatal_error("pfm_set_state(start) error errno %d\n",errno);
fds.fd = fd;
fds.events = POLLIN;
/*
* core loop
*/
for(;done == 0;) {
/*
* Must use a timeout to avoid a race condition
* with the SIGCHLD signal
*/
ret = poll(&fds, 1, 500);
/*
* if timeout expired, then check done
*/
if (ret == 0)
continue;
if (ret == -1) {
if(ret == -1 && errno == EINTR) {
warning("read interrupted, retrying\n");
continue;
}
fatal_error("poll failed: %s\n", strerror(errno));
}
ret = read(fd, &msg, sizeof(msg));
if (ret == -1)
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
* in syste-wide, interface guarantees monitoring is active
* upon return from the pfm_restart() syscall
*/
if (pfm_set_state(fd, 0, PFM_ST_RESTART) == -1)
fatal_error("pfm_set_state(restart) error errno %d\n",errno);
break;
default: fatal_error("unknown message type %d\n", msg.type);
}
}
/*
* cleanup child
*/
waitpid(pid, NULL, 0);
/*
* stop monitoring, this is required in order to guarantee that the PEBS buffer
* header is updated with the latest position, such that we see see the final
* samples
*/
if (pfm_set_state(fd, 0, PFM_ST_STOP) == -1)
fatal_error("pfm_set_state(stop) error errno %d\n",errno);
/*
* check for any leftover samples. Must have monitoring stopped
* for this operation to have guarantee it is up to date
*/
process_smpl_buf(hdr);
/*
* close session
*/
close(fd);
/*
* unmap sampling buffer and actually free the perfmon session
*/
munmap(buf_addr, (size_t)buf_arg.buf_size);
return 0;
}