From f0d2c681ac0a85142fc8abe65fc33fcad35cb9b7 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 29 Apr 2009 13:43:37 -0400 Subject: ring-buffer: add counters for commit overrun and nmi dropped entries The WARN_ON in the ring buffer when a commit is preempted and the buffer is filled by preceding writes can happen in normal operations. The WARN_ON makes it look like a bug, not to mention, because it does not stop tracing and calls printk which can also recurse, this is prone to deadlock (the WARN_ON is not in a position to recurse). This patch removes the WARN_ON and replaces it with a counter that can be retrieved by a tracer. This counter is called commit_overrun. While at it, I added a nmi_dropped counter to count any time an NMI entry is dropped because the NMI could not take the spinlock. [ Impact: prevent deadlock by printing normal case warning ] Signed-off-by: Steven Rostedt --- include/linux/ring_buffer.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 1c2f80911fb..f1345828c7c 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -153,6 +153,8 @@ unsigned long ring_buffer_entries(struct ring_buffer *buffer); unsigned long ring_buffer_overruns(struct ring_buffer *buffer); unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu); unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu); +unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu); +unsigned long ring_buffer_nmi_dropped_cpu(struct ring_buffer *buffer, int cpu); u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu); void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer, -- cgit v1.2.3