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blkftrace: binary tracing, synthesizing old format 

Impact: new feature

With this and a blkrawverify modified not to verify the sequence numbers
we can start using the userspace tools to verify that the data produced
with the ftrace plugin works as expected.

Example:

[root@f10-1 ~]# echo 1 > /sys/block/sda/sda1/trace/enable
[root@f10-1 ~]# echo bin > /d/tracing/trace_options
[root@f10-1 ~]# echo blk > /d/tracing/current_tracer
[root@f10-1 ~]# cat /d/tracing/trace_pipe > sda1.blktrace.0
^C
[root@f10-1 ~]# ./blkrawverify --noseq sda1
Verifying sda1
    CPU 0
Wrote output to sda1.verify.out
[root@f10-1 ~]# cat sda1.verify.out

---------------
Verifying sda1
    ---------------------
    Summary for cpu 0:
          1349 valid +          0 invalid (100.0%) processed

[root@f10-1 ~]#

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Arnaldo Carvalho de Melo 2009-02-02 20:30:40 -02:00 committed by Ingo Molnar
parent 2c9b238eb3
commit 08a06b83ff
1 changed files with 37 additions and 3 deletions
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40
block/blktrace.c
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@ -219,9 +219,16 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
t->sequence = ++(*sequence);
t->time = ktime_to_ns(ktime_get());
t->cpu = cpu;
t->pid = pid;
record_it:
/*
* These two are not needed in ftrace as they are in the
* generic trace_entry, filled by tracing_generic_entry_update,
* but for the trace_event->bin() synthesizer benefit we do it
* here too.
*/
t->cpu = cpu;
t->pid = pid;
t->sector = sector;
t->bytes = bytes;
t->action = what;
@ -1086,6 +1093,7 @@ static void blk_tracer_start(struct trace_array *tr)
if (blk_register_tracepoints())
atomic_dec(&blk_probes_ref);
mutex_unlock(&blk_probe_mutex);
trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
}
static int blk_tracer_init(struct trace_array *tr)
@ -1100,6 +1108,7 @@ static int blk_tracer_init(struct trace_array *tr)
static void blk_tracer_stop(struct trace_array *tr)
{
trace_flags |= TRACE_ITER_CONTEXT_INFO;
mutex_lock(&blk_probe_mutex);
if (atomic_dec_and_test(&blk_probes_ref))
blk_unregister_tracepoints();
@ -1147,6 +1156,9 @@ static int blk_trace_event_print(struct trace_iterator *iter, int flags)
const u16 what = t->action & ((1 << BLK_TC_SHIFT) - 1);
int ret;
if (trace_print_context(iter))
return TRACE_TYPE_PARTIAL_LINE;
if (unlikely(what == 0 || what > ARRAY_SIZE(what2act)))
ret = trace_seq_printf(s, "Bad pc action %x\n", what);
else {
@ -1159,6 +1171,28 @@ static int blk_trace_event_print(struct trace_iterator *iter, int flags)
return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
}
static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
const int offset = offsetof(struct blk_io_trace, sector);
struct blk_io_trace old = {
.magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
.time = ns2usecs(iter->ts),
};
if (!trace_seq_putmem(s, &old, offset))
return 0;
return trace_seq_putmem(s, &t->sector,
sizeof(old) - offset + t->pdu_len);
}
static int blk_trace_event_print_binary(struct trace_iterator *iter, int flags)
{
return blk_trace_synthesize_old_trace(iter) ?
TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
}
static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
{
const struct blk_io_trace *t;
@ -1200,7 +1234,7 @@ static struct trace_event trace_blk_event = {
.latency_trace = blk_trace_event_print,
.raw = trace_nop_print,
.hex = trace_nop_print,
.binary = trace_nop_print,
.binary = blk_trace_event_print_binary,
};
static int __init init_blk_tracer(void)