diff options
author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-03-17 17:32:32 -0400 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-03-27 16:39:01 -0400 |
commit | c9b7a4a72ff64e67b7e877a99fd652230dc26058 (patch) | |
tree | 52c419fb90561dd42e81011c073e6851020e6afd /kernel | |
parent | 06e0a548bad0f43a21e036db018e4dadb501ce8b (diff) | |
download | linux-c9b7a4a72ff64e67b7e877a99fd652230dc26058.tar.bz2 |
ring-buffer/tracing: Have iterator acknowledge dropped events
Have the ring_buffer_iterator set a flag if events were dropped as it were
to go and peek at the next event. Have the trace file display this fact if
it happened with a "LOST EVENTS" message.
Link: http://lkml.kernel.org/r/20200317213417.045858900@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/trace/ring_buffer.c | 16 | ||||
-rw-r--r-- | kernel/trace/trace.c | 16 |
2 files changed, 28 insertions, 4 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index af2f10d9f3f1..6f0b42ceeb00 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -510,6 +510,7 @@ struct ring_buffer_iter { u64 read_stamp; u64 page_stamp; struct ring_buffer_event *event; + int missed_events; }; /** @@ -1988,6 +1989,7 @@ rb_iter_head_event(struct ring_buffer_iter *iter) iter->page_stamp = iter->read_stamp = iter->head_page->page->time_stamp; iter->head = 0; iter->next_event = 0; + iter->missed_events = 1; return NULL; } @@ -4191,6 +4193,20 @@ ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts, return event; } +/** ring_buffer_iter_dropped - report if there are dropped events + * @iter: The ring buffer iterator + * + * Returns true if there was dropped events since the last peek. + */ +bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter) +{ + bool ret = iter->missed_events != 0; + + iter->missed_events = 0; + return ret; +} +EXPORT_SYMBOL_GPL(ring_buffer_iter_dropped); + /** * ring_buffer_iter_peek - peek at the next event to be read * @iter: The ring buffer iterator diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 650fa81fffe8..5e634b9c1e0a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3388,11 +3388,15 @@ peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts, struct ring_buffer_event *event; struct ring_buffer_iter *buf_iter = trace_buffer_iter(iter, cpu); - if (buf_iter) + if (buf_iter) { event = ring_buffer_iter_peek(buf_iter, ts); - else + if (lost_events) + *lost_events = ring_buffer_iter_dropped(buf_iter) ? + (unsigned long)-1 : 0; + } else { event = ring_buffer_peek(iter->array_buffer->buffer, cpu, ts, lost_events); + } if (event) { iter->ent_size = ring_buffer_event_length(event); @@ -4005,8 +4009,12 @@ enum print_line_t print_trace_line(struct trace_iterator *iter) enum print_line_t ret; if (iter->lost_events) { - trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n", - iter->cpu, iter->lost_events); + if (iter->lost_events == (unsigned long)-1) + trace_seq_printf(&iter->seq, "CPU:%d [LOST EVENTS]\n", + iter->cpu); + else + trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n", + iter->cpu, iter->lost_events); if (trace_seq_has_overflowed(&iter->seq)) return TRACE_TYPE_PARTIAL_LINE; } |