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perf top: Fall back to cpu-clock-tick hrtimer sampling if no cycle counter available

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On architectures/CPUs without PMU support but with perfcounters
enabled 'perf top' currently fails because it cannot create a
cycle based hw-perfcounter.

Fall back to the cpu-clock-tick sw-perfcounter in this case, which
is hrtimer based and will always work (as long as perfcounters
is enabled).

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2009-06-07 17:31:52 +02:00
parent 743ee1f804
commit 716c69feca
2 changed files with 73 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

113
tools/perf/builtin-top.c
View File

@ -527,58 +527,81 @@ static void mmap_read(void)
}
}
static int __cmd_top(void)
int nr_poll;
int group_fd;
static void start_counter(int i, int counter)
{
struct perf_counter_attr *attr;
pthread_t thread;
int i, counter, group_fd, nr_poll = 0;
unsigned int cpu;
cpu = profile_cpu;
if (target_pid == -1 && profile_cpu == -1)
cpu = i;
attr = attrs + counter;
attr->sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_TID;
attr->freq = freq;
try_again:
fd[i][counter] = sys_perf_counter_open(attr, target_pid, cpu, group_fd, 0);
if (fd[i][counter] < 0) {
int err = errno;
error("sys_perf_counter_open() syscall returned with %d (%s)\n",
fd[i][counter], strerror(err));
if (err == EPERM)
die(" No permission - are you root?\n");
/*
* If it's cycles then fall back to hrtimer
* based cpu-clock-tick sw counter, which
* is always available even if no PMU support:
*/
if (attr->type == PERF_TYPE_HARDWARE
&& attr->config == PERF_COUNT_CPU_CYCLES) {
warning(" ... trying to fall back to cpu-clock-ticks\n");
attr->type = PERF_TYPE_SOFTWARE;
attr->config = PERF_COUNT_CPU_CLOCK;
goto try_again;
}
exit(-1);
}
assert(fd[i][counter] >= 0);
fcntl(fd[i][counter], F_SETFL, O_NONBLOCK);
/*
* First counter acts as the group leader:
*/
if (group && group_fd == -1)
group_fd = fd[i][counter];
event_array[nr_poll].fd = fd[i][counter];
event_array[nr_poll].events = POLLIN;
nr_poll++;
mmap_array[i][counter].counter = counter;
mmap_array[i][counter].prev = 0;
mmap_array[i][counter].mask = mmap_pages*page_size - 1;
mmap_array[i][counter].base = mmap(NULL, (mmap_pages+1)*page_size,
PROT_READ, MAP_SHARED, fd[i][counter], 0);
if (mmap_array[i][counter].base == MAP_FAILED)
die("failed to mmap with %d (%s)\n", errno, strerror(errno));
}
static int __cmd_top(void)
{
pthread_t thread;
int i, counter;
int ret;
for (i = 0; i < nr_cpus; i++) {
group_fd = -1;
for (counter = 0; counter < nr_counters; counter++) {
cpu = profile_cpu;
if (target_pid == -1 && profile_cpu == -1)
cpu = i;
attr = attrs + counter;
attr->sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_TID;
attr->freq = freq;
fd[i][counter] = sys_perf_counter_open(attr, target_pid, cpu, group_fd, 0);
if (fd[i][counter] < 0) {
int err = errno;
error("syscall returned with %d (%s)\n",
fd[i][counter], strerror(err));
if (err == EPERM)
printf("Are you root?\n");
exit(-1);
}
assert(fd[i][counter] >= 0);
fcntl(fd[i][counter], F_SETFL, O_NONBLOCK);
/*
* First counter acts as the group leader:
*/
if (group && group_fd == -1)
group_fd = fd[i][counter];
event_array[nr_poll].fd = fd[i][counter];
event_array[nr_poll].events = POLLIN;
nr_poll++;
mmap_array[i][counter].counter = counter;
mmap_array[i][counter].prev = 0;
mmap_array[i][counter].mask = mmap_pages*page_size - 1;
mmap_array[i][counter].base = mmap(NULL, (mmap_pages+1)*page_size,
PROT_READ, MAP_SHARED, fd[i][counter], 0);
if (mmap_array[i][counter].base == MAP_FAILED)
die("failed to mmap with %d (%s)\n", errno, strerror(errno));
}
for (counter = 0; counter < nr_counters; counter++)
start_counter(i, counter);
}
/* Wait for a minimal set of events before starting the snapshot */

10
tools/perf/util/usage.c
View File

@ -9,29 +9,29 @@ static void report(const char *prefix, const char *err, va_list params)
{
char msg[1024];
vsnprintf(msg, sizeof(msg), err, params);
fprintf(stderr, "%s%s\n", prefix, msg);
fprintf(stderr, " %s%s\n", prefix, msg);
}
static NORETURN void usage_builtin(const char *err)
{
fprintf(stderr, "\n usage: %s\n", err);
fprintf(stderr, "\n Usage: %s\n", err);
exit(129);
}
static NORETURN void die_builtin(const char *err, va_list params)
{
report("fatal: ", err, params);
report(" Fatal: ", err, params);
exit(128);
}
static void error_builtin(const char *err, va_list params)
{
report("error: ", err, params);
report(" Error: ", err, params);
}
static void warn_builtin(const char *warn, va_list params)
{
report("warning: ", warn, params);
report(" Warning: ", warn, params);
}
/* If we are in a dlopen()ed .so write to a global variable would segfault