/*
* task_smpl.c - example of a task sampling another one using a randomized sampling period
*
* Copyright (c) 2003-2006 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/ia64.
*/
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <stdarg.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <perfmon/perfmon.h>
#include <perfmon/perfmon_default_smpl.h>
#include <perfmon/pfmlib.h>
typedef pfm_default_smpl_arg_t smpl_fmt_arg_t;
typedef pfm_default_smpl_hdr_t smpl_hdr_t;
typedef pfm_default_smpl_entry_t smpl_entry_t;
typedef pfm_default_smpl_ctx_arg_t ctx_arg_t;
typedef int ctxid_t;
#define FMT_UUID PFM_DEFAULT_SMPL_UUID
#define NUM_PMCS PFMLIB_MAX_PMCS
#define NUM_PMDS PFMLIB_MAX_PMDS
#define FIRST_COUNTER 4
static unsigned long collect_samples;
static void *buf_addr;
static pfm_uuid_t buf_fmt_id = FMT_UUID;
static void fatal_error(char *fmt,...) __attribute__((noreturn));
static void
warning(char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
}
static void
fatal_error(char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
exit(1);
}
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 __inline__ int
bit_weight(unsigned long x)
{
int sum = 0;
for (; x ; x>>=1) {
if (x & 0x1UL) sum++;
}
return sum;
}
static void
process_smpl_buf(int id, unsigned long smpl_pmd_mask, int need_restart)
{
static unsigned long last_overflow = ~0UL; /* initialize to biggest value possible */
smpl_hdr_t *hdr = (smpl_hdr_t *)buf_addr;
smpl_entry_t *ent;
unsigned long count, entry, *reg, pos, msk;
unsigned long entry_size;
int j;
printf("processing %s buffer at %p\n", need_restart==0 ? "leftover" : "", hdr);
if (hdr->hdr_overflows <= last_overflow && last_overflow != ~0UL) {
warning("skipping identical set of samples %lu <= %lu\n",
hdr->hdr_overflows, last_overflow);
return;
}
last_overflow = hdr->hdr_overflows;
count = hdr->hdr_count;
ent = (smpl_entry_t *)(hdr+1);
pos = (unsigned long)ent;
entry = collect_samples;
/*
* in this example program, we use fixed-size entries, therefore we
* can compute the entry size in advance. Perfmon-2 supports variable
* size entries.
*/
entry_size = sizeof(smpl_entry_t)+(bit_weight(smpl_pmd_mask)<<3);
while(count--) {
printf("entry %ld PID:%d CPU:%d IIP:0x%016lx\n",
entry,
ent->pid,
ent->cpu,
ent->ip);
printf("\tOVFL: %d LAST_VAL: %lu\n", ent->ovfl_pmd, -ent->last_reset_val);
/*
* print body: additional PMDs recorded
* PMD are recorded in increasing index order
*/
reg = (unsigned long *)(ent+1);
for(j=0, msk = smpl_pmd_mask; msk; msk >>=1, j++) {
if ((msk & 0x1) == 0) continue;
printf("PMD%-2d = 0x%016lx\n", j, *reg);
reg++;
}
/*
* we could have removed this and used:
* ent = (smpl_entry_t *)reg
* instead.
*/
pos += entry_size;
ent = (smpl_entry_t *)pos;
entry++;
}
collect_samples = entry;
/*
* 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 (need_restart && perfmonctl(id, PFM_RESTART, 0, 0) == -1) {
if (errno != EBUSY)
fatal_error("perfmonctl error PFM_RESTART errno %d\n",errno);
else
warning("PFM_RESTART: task has probably terminated \n");
}
}
int
mainloop(char **arg)
{
ctx_arg_t ctx;
pfmlib_input_param_t inp;
pfmlib_output_param_t outp;
pfarg_reg_t pd[NUM_PMDS];
pfarg_reg_t pc[NUM_PMCS];
pfarg_load_t load_args;
pfm_msg_t msg;
unsigned long ovfl_count = 0UL;
unsigned long sample_period;
unsigned long smpl_pmd_mask = 0UL;
pid_t pid;
int status, ret, fd;
unsigned int i, num_counters;
/*
* intialize all locals
*/
memset(&ctx, 0, sizeof(ctx));
memset(&inp,0, sizeof(inp));
memset(&outp,0, sizeof(outp));
memset(pd, 0, sizeof(pd));
memset(pc, 0, sizeof(pc));
/*
* locate events
*/
pfm_get_num_counters(&num_counters);
if (pfm_get_cycle_event(&inp.pfp_events[0]) != PFMLIB_SUCCESS)
fatal_error("cannot find cycle event\n");
if (pfm_get_inst_retired_event(&inp.pfp_events[1]) != PFMLIB_SUCCESS)
fatal_error("cannot find inst retired event\n");
i = 2;
if (i > num_counters) {
i = num_counters;
printf("too many events provided (max=%d events), using first %d event(s)\n", num_counters, i);
}
/*
* set the privilege mode:
* PFM_PLM3 : user level
* PFM_PLM0 : kernel level
*/
inp.pfp_dfl_plm = PFM_PLM3;
/*
* how many counters we use
*/
inp.pfp_event_count = i;
/*
* let the library figure out the values for the PMCS
*/
if ((ret=pfm_dispatch_events(&inp, NULL, &outp, NULL)) != PFMLIB_SUCCESS) {
fatal_error("cannot configure events: %s\n", pfm_strerror(ret));
}
/*
* Now prepare the argument to initialize the PMDs and PMCS.
* We must pfp_pmc_count to determine the number of PMC to intialize.
* We must use pfp_event_count to determine the number of PMD to initialize.
* Some events causes extra PMCs to be used, so pfp_pmc_count may be >= pfp_event_count.
*
* This step is new compared to libpfm-2.x. It is necessary because the library no
* longer knows about the kernel data structures.
*/
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;
}
/*
* the PMC controlling the event ALWAYS come first, that's why this loop
* is safe even when extra PMC are needed to support a particular event.
*/
for (i=0; i < inp.pfp_event_count; i++) {
pd[i].reg_num = pc[i].reg_num;
/* build sampling mask */
smpl_pmd_mask |= 1UL << pc[i].reg_num;
}
printf("smpl_pmd_mask=0x%lx\n", smpl_pmd_mask);
/*
* now we indicate what to record when each counter overflows.
* In our case, we only have one sampling period and it is set for the
* first event. Here we indicate that when the sampling period expires
* then we want to record the value of all the other counters.
*
* We exclude the first counter in this case.
*/
smpl_pmd_mask &= ~(1UL << pc[0].reg_num);
pc[0].reg_smpl_pmds[0] = smpl_pmd_mask;
/*
* we our sampling counter overflow, we want to be notified.
* The notification will come ONLY when the sampling buffer
* becomes full.
*
* We also activate randomization of the sampling period.
*/
pc[0].reg_flags |= PFM_REGFL_OVFL_NOTIFY | PFM_REGFL_RANDOM;
/*
* we also want to reset the other PMDs on
* every overflow. If we do not set
* this, the non-overflowed counters
* will be untouched.
*/
pc[0].reg_reset_pmds[0] |= smpl_pmd_mask;
sample_period = 1000000UL;
pd[0].reg_value = (~0) - sample_period + 1;
pd[0].reg_short_reset = (~0) - sample_period + 1;
pd[0].reg_long_reset = (~0) - sample_period + 1;
/*
* setup randomization parameters, we allow a range of up to +256 here.
*/
pd[0].reg_random_seed = 5;
pd[0].reg_random_mask = 0xff;
printf("programming %u PMCS and %u PMDS\n", outp.pfp_pmc_count, inp.pfp_event_count);
/*
* prepare context structure.
*
* format specific parameters MUST be concatenated to the regular
* pfarg_context_t structure. For convenience, the default sampling
* format provides a data structure that already combines the pfarg_context_t
* with what is needed fot this format.
*/
/*
* We initialize the format specific information.
* The format is identified by its UUID which must be copied
* into the ctx_buf_fmt_id field.
*/
memcpy(ctx.ctx_arg.ctx_smpl_buf_id, buf_fmt_id, sizeof(pfm_uuid_t));
/*
* the size of the buffer is indicated in bytes (not entries).
*
* The kernel will record into the buffer up to a certain point.
* No partial samples are ever recorded.
*/
ctx.buf_arg.buf_size = 8192;
/*
* now create our perfmon context.
*/
if (perfmonctl(0, PFM_CREATE_CONTEXT, &ctx, 1) == -1 ) {
if (errno == ENOSYS) {
fatal_error("Your kernel does not have performance monitoring support!\n");
}
fatal_error("Can't create PFM context %s\n", strerror(errno));
}
/*
* extract the file descriptor we will use to
* identify this newly created context
*/
fd = ctx.ctx_arg.ctx_fd;
/*
* retrieve the virtual address at which the sampling
* buffer has been mapped
*/
buf_addr = ctx.ctx_arg.ctx_smpl_vaddr;
printf("context [%d] buffer mapped @%p\n", fd, buf_addr);
/*
* Now program the registers
*/
if (perfmonctl(fd, PFM_WRITE_PMCS, pc, outp.pfp_pmc_count) == -1) {
fatal_error("perfmonctl error PFM_WRITE_PMCS errno %d\n",errno);
}
/*
* initialize the PMDs
*/
if (perfmonctl(fd, PFM_WRITE_PMDS, pd, inp.pfp_event_count) == -1) {
fatal_error("perfmonctl error PFM_WRITE_PMDS errno %d\n",errno);
}
/*
* 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 context. 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(arg);
}
/*
* 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", arg[0], pid, WEXITSTATUS(status));
goto terminate_session;
}
/*
* attach context to stopped task
*/
load_args.load_pid = pid;
if (perfmonctl(fd, PFM_LOAD_CONTEXT, &load_args, 1) == -1) {
fatal_error("perfmonctl error PFM_LOAD_CONTEXT errno %d\n",errno);
}
/*
* activate monitoring for stopped task.
* (nothing will be measured at this point
*/
if (perfmonctl(fd, PFM_START, NULL, 0) == -1) {
fatal_error(" perfmonctl error PFM_START 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) {
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(fd, smpl_pmd_mask, 1);
ovfl_count++;
break;
case PFM_MSG_END: /* monitored task terminated */
printf("task terminated\n");
goto terminate_session;
default: fatal_error("unknown message type %d\n", msg.type);
}
}
terminate_session:
/*
* cleanup child
*/
waitpid(pid, &status, 0);
/*
* check for any leftover samples
*/
process_smpl_buf(fd, smpl_pmd_mask, 0);
/*
* destroy perfmon context
*/
close(fd);
printf("%lu samples collected in %lu buffer overflows\n", collect_samples, ovfl_count);
return 0;
}
int
main(int argc, char **argv)
{
pfmlib_options_t pfmlib_options;
if (argc < 2)
fatal_error("You must specify a command to execute\n");
/*
* Initialize pfm library (required before we can use it)
*/
if (pfm_initialize() != PFMLIB_SUCCESS) {
fatal_error("Can't initialize library\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 = 0; /* set to 1 for verbose */
pfm_set_options(&pfmlib_options);
return mainloop(argv+1);
}