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perf record: Fall back to cpu-clock-ticks if no PMU

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On architectures/CPUs without PMU support but with perfcounters
enabled 'perf record' 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
are 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 17:39:02 +02:00
parent 716c69feca
commit 3da297a60f
2 changed files with 33 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
tools/perf/builtin-record.c
View File

@ -37,6 +37,7 @@ static pid_t target_pid = -1;
static int inherit = 1;
static int force = 0;
static int append_file = 0;
static int verbose = 0;
static long samples;
static struct timeval last_read;
@ -349,17 +350,35 @@ static void create_counter(int counter, int cpu, pid_t pid)
track = 0; /* only the first counter needs these */
try_again:
fd[nr_cpu][counter] = sys_perf_counter_open(attr, pid, cpu, group_fd, 0);
if (fd[nr_cpu][counter] < 0) {
int err = errno;
error("syscall returned with %d (%s)\n",
if (verbose)
error("sys_perf_counter_open() syscall returned with %d (%s)\n",
fd[nr_cpu][counter], strerror(err));
if (err == EPERM)
printf("Are you root?\n");
die("Permission error - 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) {
if (verbose)
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[nr_cpu][counter] >= 0);
fcntl(fd[nr_cpu][counter], F_SETFL, O_NONBLOCK);
@ -519,6 +538,8 @@ static const struct option options[] = {
"profile at this frequency"),
OPT_INTEGER('m', "mmap-pages", &mmap_pages,
"number of mmap data pages"),
OPT_BOOLEAN('v', "verbose", &verbose,
"be more verbose (show counter open errors, etc)"),
OPT_END()
};

14
tools/perf/builtin-top.c
View File

@ -65,6 +65,7 @@ static int group = 0;
static unsigned int page_size;
static unsigned int mmap_pages = 16;
static int freq = 0;
static int verbose = 0;
static char *sym_filter;
static unsigned long filter_start;
@ -550,11 +551,12 @@ try_again:
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 (verbose)
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");
die("No permission - are you root?\n");
/*
* If it's cycles then fall back to hrtimer
* based cpu-clock-tick sw counter, which
@ -563,7 +565,9 @@ try_again:
if (attr->type == PERF_TYPE_HARDWARE
&& attr->config == PERF_COUNT_CPU_CYCLES) {
warning(" ... trying to fall back to cpu-clock-ticks\n");
if (verbose)
warning(" ... trying to fall back to cpu-clock-ticks\n");
attr->type = PERF_TYPE_SOFTWARE;
attr->config = PERF_COUNT_CPU_CLOCK;
goto try_again;
@ -673,6 +677,8 @@ static const struct option options[] = {
"profile at this frequency"),
OPT_INTEGER('E', "entries", &print_entries,
"display this many functions"),
OPT_BOOLEAN('v', "verbose", &verbose,
"be more verbose (show counter open errors, etc)"),
OPT_END()
};