Skip to content

Commit

Permalink
perf_counter tools: Handle lost events
Browse files Browse the repository at this point in the history
Make use of the new ->data_tail mechanism to tell kernel-space
about user-space draining the data stream. Emit lost events
(and display them) if they happen.

Signed-off-by: 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>
  • Loading branch information
Peter Zijlstra authored and Ingo Molnar committed Jun 18, 2009
1 parent 43a21ea commit 9d91a6f
Show file tree
Hide file tree
Showing 2 changed files with 44 additions and 5 deletions.
20 changes: 16 additions & 4 deletions tools/perf/builtin-record.c
Original file line number Diff line number Diff line change
Expand Up @@ -78,17 +78,28 @@ struct mmap_data {

static struct mmap_data mmap_array[MAX_NR_CPUS][MAX_COUNTERS];

static unsigned int mmap_read_head(struct mmap_data *md)
static unsigned long mmap_read_head(struct mmap_data *md)
{
struct perf_counter_mmap_page *pc = md->base;
int head;
long head;

head = pc->data_head;
rmb();

return head;
}

static void mmap_write_tail(struct mmap_data *md, unsigned long tail)
{
struct perf_counter_mmap_page *pc = md->base;

/*
* ensure all reads are done before we write the tail out.
*/
/* mb(); */
pc->data_tail = tail;
}

static void mmap_read(struct mmap_data *md)
{
unsigned int head = mmap_read_head(md);
Expand All @@ -109,7 +120,7 @@ static void mmap_read(struct mmap_data *md)
* In either case, truncate and restart at head.
*/
diff = head - old;
if (diff > md->mask / 2 || diff < 0) {
if (diff < 0) {
struct timeval iv;
unsigned long msecs;

Expand Down Expand Up @@ -167,6 +178,7 @@ static void mmap_read(struct mmap_data *md)
}

md->prev = old;
mmap_write_tail(md, old);
}

static volatile int done = 0;
Expand Down Expand Up @@ -424,7 +436,7 @@ static void create_counter(int counter, int cpu, pid_t pid)
mmap_array[nr_cpu][counter].prev = 0;
mmap_array[nr_cpu][counter].mask = mmap_pages*page_size - 1;
mmap_array[nr_cpu][counter].base = mmap(NULL, (mmap_pages+1)*page_size,
PROT_READ, MAP_SHARED, fd[nr_cpu][counter], 0);
PROT_READ|PROT_WRITE, MAP_SHARED, fd[nr_cpu][counter], 0);
if (mmap_array[nr_cpu][counter].base == MAP_FAILED) {
error("failed to mmap with %d (%s)\n", errno, strerror(errno));
exit(-1);
Expand Down
29 changes: 28 additions & 1 deletion tools/perf/builtin-report.c
Original file line number Diff line number Diff line change
Expand Up @@ -83,13 +83,20 @@ struct period_event {
__u64 sample_period;
};

struct lost_event {
struct perf_event_header header;
__u64 id;
__u64 lost;
};

typedef union event_union {
struct perf_event_header header;
struct ip_event ip;
struct mmap_event mmap;
struct comm_event comm;
struct fork_event fork;
struct period_event period;
struct lost_event lost;
} event_t;

static LIST_HEAD(dsos);
Expand Down Expand Up @@ -1068,7 +1075,8 @@ static unsigned long total = 0,
total_mmap = 0,
total_comm = 0,
total_fork = 0,
total_unknown = 0;
total_unknown = 0,
total_lost = 0;

static int validate_chain(struct perf_callchain_entry *chain, event_t *event)
{
Expand Down Expand Up @@ -1260,6 +1268,20 @@ process_period_event(event_t *event, unsigned long offset, unsigned long head)
return 0;
}

static int
process_lost_event(event_t *event, unsigned long offset, unsigned long head)
{
dprintf("%p [%p]: PERF_EVENT_LOST: id:%Ld: lost:%Ld\n",
(void *)(offset + head),
(void *)(long)(event->header.size),
event->lost.id,
event->lost.lost);

total_lost += event->lost.lost;

return 0;
}

static void trace_event(event_t *event)
{
unsigned char *raw_event = (void *)event;
Expand Down Expand Up @@ -1316,6 +1338,10 @@ process_event(event_t *event, unsigned long offset, unsigned long head)

case PERF_EVENT_PERIOD:
return process_period_event(event, offset, head);

case PERF_EVENT_LOST:
return process_lost_event(event, offset, head);

/*
* We dont process them right now but they are fine:
*/
Expand Down Expand Up @@ -1444,6 +1470,7 @@ static int __cmd_report(void)
dprintf(" mmap events: %10ld\n", total_mmap);
dprintf(" comm events: %10ld\n", total_comm);
dprintf(" fork events: %10ld\n", total_fork);
dprintf(" lost events: %10ld\n", total_lost);
dprintf(" unknown events: %10ld\n", total_unknown);

if (dump_trace)
Expand Down

0 comments on commit 9d91a6f

Please sign in to comment.