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Commit 391b170f authored by Pekka Paalanen's avatar Pekka Paalanen Committed by Ingo Molnar
Browse files

mmiotrace: count events lost due to not recording 



Impact: enhances lost events counting in mmiotrace

The tracing framework, or the ring buffer facility it uses, has a switch
to stop recording data. When recording is off, the trace events will be
lost. The framework does not count these, so mmiotrace has to count them
itself.

Signed-off-by: default avatarPekka Paalanen <pq@iki.fi>
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d2f8d7ee

kernel/trace/trace_mmiotrace.c

+10 −4
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#include <linux/kernel.h>

#include <linux/mmiotrace.h>

#include <linux/pci.h>

#include <asm/atomic.h>



#include "trace.h"
@@ -19,6 +20,7 @@ struct header_iter { 
static struct trace_array *mmio_trace_array;

static bool overrun_detected;

static unsigned long prev_overruns;

static atomic_t dropped_count;



static void mmio_reset_data(struct trace_array *tr)

{
@@ -121,11 +123,11 @@ static void mmio_close(struct trace_iterator *iter) 


static unsigned long count_overruns(struct trace_iterator *iter)

{

	unsigned long cnt = 0;

	unsigned long cnt = atomic_xchg(&dropped_count, 0);

	unsigned long over = ring_buffer_overruns(iter->tr->buffer);



	if (over > prev_overruns)

		cnt = over - prev_overruns;

		cnt += over - prev_overruns;

	prev_overruns = over;

	return cnt;

}
@@ -310,8 +312,10 @@ static void __trace_mmiotrace_rw(struct trace_array *tr, 


	event	= ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),

					   &irq_flags);

	if (!event)

	if (!event) {

		atomic_inc(&dropped_count);

		return;

	}

	entry	= ring_buffer_event_data(event);

	tracing_generic_entry_update(&entry->ent, 0, preempt_count());

	entry->ent.type			= TRACE_MMIO_RW;
@@ -338,8 +342,10 @@ static void __trace_mmiotrace_map(struct trace_array *tr, 


	event	= ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),

					   &irq_flags);

	if (!event)

	if (!event) {

		atomic_inc(&dropped_count);

		return;

	}

	entry	= ring_buffer_event_data(event);

	tracing_generic_entry_update(&entry->ent, 0, preempt_count());

	entry->ent.type			= TRACE_MMIO_MAP;