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mmiotrace: count events lost due to not recording

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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: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Pekka Paalanen 2009-01-06 13:57:11 +02:00 • committed by Ingo Molnar
parent fe6f90e57f
commit 173ed24ee2
1 changed files with 10 additions and 4 deletions
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14
kernel/trace/trace_mmiotrace.c
View file

@ -9,6 +9,7 @@
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/mmiotrace.h> #include <linux/mmiotrace.h>
#include <linux/pci.h> #include <linux/pci.h>
#include <asm/atomic.h>
#include "trace.h" #include "trace.h"
#include "trace_output.h" #include "trace_output.h"
@ -20,6 +21,7 @@ struct header_iter {
static struct trace_array *mmio_trace_array; static struct trace_array *mmio_trace_array;
static bool overrun_detected; static bool overrun_detected;
static unsigned long prev_overruns; static unsigned long prev_overruns;
static atomic_t dropped_count;
static void mmio_reset_data(struct trace_array *tr) static void mmio_reset_data(struct trace_array *tr)
{ {
@ -122,11 +124,11 @@ static void mmio_close(struct trace_iterator *iter)
static unsigned long count_overruns(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); unsigned long over = ring_buffer_overruns(iter->tr->buffer);
if (over > prev_overruns) if (over > prev_overruns)
cnt = over - prev_overruns; cnt += over - prev_overruns;
prev_overruns = over; prev_overruns = over;
return cnt; return cnt;
} }
@ -308,8 +310,10 @@ static void __trace_mmiotrace_rw(struct trace_array *tr,
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags); &irq_flags);
if (!event) if (!event) {
atomic_inc(&dropped_count);
return; return;
}
entry = ring_buffer_event_data(event); entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, 0, preempt_count()); tracing_generic_entry_update(&entry->ent, 0, preempt_count());
entry->ent.type = TRACE_MMIO_RW; entry->ent.type = TRACE_MMIO_RW;
@ -336,8 +340,10 @@ static void __trace_mmiotrace_map(struct trace_array *tr,
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags); &irq_flags);
if (!event) if (!event) {
atomic_inc(&dropped_count);
return; return;
}
entry = ring_buffer_event_data(event); entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, 0, preempt_count()); tracing_generic_entry_update(&entry->ent, 0, preempt_count());
entry->ent.type = TRACE_MMIO_MAP; entry->ent.type = TRACE_MMIO_MAP;