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Use the SET_OUTPUT ioctl to direct all output to the same buffer

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This ensures that we don't get events out of order, which will make
the profiles look a lot less bogus on multi-core systems.
This commit is contained in:
Søren Sandmann Pedersen
2010-04-24 10:49:18 -04:00
parent 539c3a8754
commit c960ebd52f
2 changed files with 53 additions and 30 deletions
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82
collector.c
View File

@ -379,9 +379,30 @@ map_buffer (counter_t *counter, GError **err)
return address;
}
static gboolean
counter_set_output (counter_t *counter, int output)
{
return ioctl (counter->fd, PERF_COUNTER_IOC_SET_OUTPUT, output) == 0;
}
static void
counter_enable (counter_t *counter)
{
ioctl (counter->fd, PERF_COUNTER_IOC_ENABLE);
}
static void
counter_disable (counter_t *counter)
{
d_print ("disable\n");
ioctl (counter->fd, PERF_COUNTER_IOC_DISABLE);
}
static counter_t *
counter_new (Collector *collector,
int cpu,
counter_t *output,
GError **err)
{
struct perf_counter_attr attr;
@ -417,40 +438,35 @@ counter_new (Collector *collector,
if (fd < 0)
return fail (err, "Could not open performance counter");
counter->collector = collector;
counter->fd = fd;
counter->mmap_page = map_buffer (counter, err);
if (!counter->mmap_page || counter->mmap_page == MAP_FAILED)
return NULL;
counter->data = (uint8_t *)counter->mmap_page + get_page_size ();
counter->tail = 0;
counter->cpu = cpu;
fd_add_watch (fd, counter);
fd_set_read_callback (fd, on_read);
if (output && counter_set_output (counter, output->fd))
{
counter->mmap_page = NULL;
counter->data = NULL;
counter->tail = 0;
}
else
{
counter->mmap_page = map_buffer (counter, err);
if (!counter->mmap_page || counter->mmap_page == MAP_FAILED)
return NULL;
counter->data = (uint8_t *)counter->mmap_page + get_page_size ();
counter->tail = 0;
fd_add_watch (fd, counter);
fd_set_read_callback (fd, on_read);
}
return counter;
}
static void
counter_enable (counter_t *counter)
{
ioctl (counter->fd, PERF_COUNTER_IOC_ENABLE);
}
static void
counter_disable (counter_t *counter)
{
d_print ("disable\n");
ioctl (counter->fd, PERF_COUNTER_IOC_DISABLE);
}
static void
counter_free (counter_t *counter)
{
@ -705,13 +721,15 @@ collector_start (Collector *collector,
{
int n_cpus = get_n_cpus ();
int i;
counter_t *output;
if (!collector->tracker)
collector->tracker = tracker_new ();
output = NULL;
for (i = 0; i < n_cpus; ++i)
{
counter_t *counter = counter_new (collector, i, err);
counter_t *counter = counter_new (collector, i, output, err);
if (!counter)
{
@ -724,8 +742,11 @@ collector_start (Collector *collector,
return FALSE;
}
collector->counters = g_list_append (collector->counters, counter);
if (!output)
output = counter;
}
enable_counters (collector);
@ -746,7 +767,8 @@ collector_stop (Collector *collector)
{
counter_t *counter = list->data;
on_read (counter);
if (counter->data)
on_read (counter);
counter_free (counter);
}

1
perf_counter.h
View File

@ -216,6 +216,7 @@ struct perf_counter_attr {
#define PERF_COUNTER_IOC_REFRESH _IO ('$', 2)
#define PERF_COUNTER_IOC_RESET _IO ('$', 3)
#define PERF_COUNTER_IOC_PERIOD _IOW('$', 4, u64)
#define PERF_COUNTER_IOC_SET_OUTPUT _IO ('$', 5)
enum perf_counter_ioc_flags {
PERF_IOC_FLAG_GROUP = 1U << 0,