diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/perf_counter/kerneltop.c | 65 |
1 files changed, 59 insertions, 6 deletions
diff --git a/Documentation/perf_counter/kerneltop.c b/Documentation/perf_counter/kerneltop.c index 3e45bf6591b..fda1438365d 100644 --- a/Documentation/perf_counter/kerneltop.c +++ b/Documentation/perf_counter/kerneltop.c @@ -134,6 +134,11 @@ #endif #define unlikely(x) __builtin_expect(!!(x), 0) +#define min(x, y) ({ \ + typeof(x) _min1 = (x); \ + typeof(y) _min2 = (y); \ + (void) (&_min1 == &_min2); \ + _min1 < _min2 ? _min1 : _min2; }) asmlinkage int sys_perf_counter_open( struct perf_counter_hw_event *hw_event_uptr __user, @@ -178,7 +183,7 @@ static int nr_cpus = 0; static int nmi = 1; static int group = 0; static unsigned int page_size; -static unsigned int mmap_pages = 4; +static unsigned int mmap_pages = 16; static char *vmlinux; @@ -1147,28 +1152,75 @@ static void mmap_read(struct mmap_data *md) unsigned int head = mmap_read_head(md); unsigned int old = md->prev; unsigned char *data = md->base + page_size; + int diff; gettimeofday(&this_read, NULL); - if (head - old > md->mask) { + /* + * If we're further behind than half the buffer, there's a chance + * the writer will bite our tail and screw up the events under us. + * + * If we somehow ended up ahead of the head, we got messed up. + * + * In either case, truncate and restart at head. + */ + diff = head - old; + if (diff > md->mask / 2 || diff < 0) { struct timeval iv; unsigned long msecs; timersub(&this_read, &last_read, &iv); msecs = iv.tv_sec*1000 + iv.tv_usec/1000; - fprintf(stderr, "WARNING: failed to keep up with mmap data. Last read %lu msecs ago.\n", msecs); + fprintf(stderr, "WARNING: failed to keep up with mmap data." + " Last read %lu msecs ago.\n", msecs); + /* + * head points to a known good entry, start there. + */ old = head; } last_read = this_read; for (; old != head;) { - __u64 *ptr = (__u64 *)&data[old & md->mask]; - old += sizeof(__u64); + struct event_struct { + struct perf_event_header header; + __u64 ip; + __u32 pid, tid; + } *event = (struct event_struct *)&data[old & md->mask]; + struct event_struct event_copy; + + unsigned int size = event->header.size; + + /* + * Event straddles the mmap boundary -- header should always + * be inside due to u64 alignment of output. + */ + if ((old & md->mask) + size != ((old + size) & md->mask)) { + unsigned int offset = old; + unsigned int len = sizeof(*event), cpy; + void *dst = &event_copy; + + do { + cpy = min(md->mask + 1 - (offset & md->mask), len); + memcpy(dst, &data[offset & md->mask], cpy); + offset += cpy; + dst += cpy; + len -= cpy; + } while (len); + + event = &event_copy; + } - process_event(*ptr, md->counter); + old += size; + + switch (event->header.type) { + case PERF_EVENT_IP: + case PERF_EVENT_IP | __PERF_EVENT_TID: + process_event(event->ip, md->counter); + break; + } } md->prev = old; @@ -1214,6 +1266,7 @@ int main(int argc, char *argv[]) hw_event.irq_period = event_count[counter]; hw_event.record_type = PERF_RECORD_IRQ; hw_event.nmi = nmi; + hw_event.include_tid = 1; fd[i][counter] = sys_perf_counter_open(&hw_event, tid, cpu, group_fd, 0); if (fd[i][counter] < 0) { |