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| author | Pekka Paalanen <pq@iki.fi> | 2008-11-23 21:24:30 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-11-23 20:33:23 +0100 |
| commit | 7ee1768ddb3075ae3a0801cc2d0ea4195530a7db (patch) | |
| tree | 403dea91103838cbe56bca586a8f41a470e7a1e4 /kernel | |
| parent | 522a110b42b306d696cf84e34c677ed0e7080194 (diff) | |
| download | lwn-7ee1768ddb3075ae3a0801cc2d0ea4195530a7db.tar.gz lwn-7ee1768ddb3075ae3a0801cc2d0ea4195530a7db.zip | |
x86, mmiotrace: fix buffer overrun detection
Impact: fix mmiotrace overrun tracing
When ftrace framework moved to use the ring buffer facility, the buffer
overrun detection was broken after 2.6.27 by commit
| commit 3928a8a2d98081d1bc3c0a84a2d70e29b90ecf1c
| Author: Steven Rostedt <rostedt@goodmis.org>
| Date: Mon Sep 29 23:02:41 2008 -0400
|
| ftrace: make work with new ring buffer
|
| This patch ports ftrace over to the new ring buffer.
The detection is now fixed by using the ring buffer API.
When mmiotrace detects a buffer overrun, it will report the number of
lost events. People reading an mmiotrace log must know if something was
missed, otherwise the data may not make sense.
Signed-off-by: Pekka Paalanen <pq@iki.fi>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace_mmiotrace.c | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c index f28484618ff0..e62cbf78eab6 100644 --- a/kernel/trace/trace_mmiotrace.c +++ b/kernel/trace/trace_mmiotrace.c @@ -18,12 +18,14 @@ struct header_iter { static struct trace_array *mmio_trace_array; static bool overrun_detected; +static unsigned long prev_overruns; static void mmio_reset_data(struct trace_array *tr) { int cpu; overrun_detected = false; + prev_overruns = 0; tr->time_start = ftrace_now(tr->cpu); for_each_online_cpu(cpu) @@ -128,16 +130,12 @@ static void mmio_close(struct trace_iterator *iter) static unsigned long count_overruns(struct trace_iterator *iter) { - int cpu; unsigned long cnt = 0; -/* FIXME: */ -#if 0 - for_each_online_cpu(cpu) { - cnt += iter->overrun[cpu]; - iter->overrun[cpu] = 0; - } -#endif - (void)cpu; + unsigned long over = ring_buffer_overruns(iter->tr->buffer); + + if (over > prev_overruns) + cnt = over - prev_overruns; + prev_overruns = over; return cnt; } |