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Subject[tip:tracing/blktrace] blktrace: print out BLK_TN_MESSAGE properly
Commit-ID:  36edcee82b04a201500529ec1257a303ad002e7d
Gitweb: http://git.kernel.org/tip/36edcee82b04a201500529ec1257a303ad002e7d
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Fri, 27 Mar 2009 10:21:54 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 30 Mar 2009 03:16:32 +0200

blktrace: print out BLK_TN_MESSAGE properly

Impact: improve ftrace plugin output

Before this patch:

# cat trace
make-5383 [001] 741.240059: 8,7 P N [make]
__trace_note_message: cfq1074

# echo 1 > options/blk_classic
# cat trace
8,7 1 0.692221252 0 C W 130411392 + 1024 [0]
Bad pc action 6361
Bad pc action 283d

# echo 0 > options/blk_classic
# echo bin > trace_options
# cat trace_pipe | blkparse -i -
(can't parse messages generated by blk_add_trace_msg())

After this patch:
# cat trace
<idle>-0 [001] 187.600933: 8,7 C W 145220224 + 8 [0]
<idle>-0 [001] 187.600946: 8,7 m N cfq1076 complete

# echo 1 > options/blk_classic
# cat trace
8,7 1 0.256378996 238 I W 113190728 + 8 [pdflush]
8,7 1 0.256378998 238 m N cfq1076 insert_request

# echo 0 > options/blk_classic
# echo bin > trace_options
# cat trace_pipe | blkparse -i -
8,7 1 0 22.973250293 0 C W 102770576 + 8 [0]
8,7 1 0 22.973259213 0 m N cfq1076 complete

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49CC3842.60608@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
kernel/trace/blktrace.c | 80 +++++++++++++++++++++++++++++++++++-----------
1 files changed, 61 insertions(+), 19 deletions(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index c103b0c..947c5b3 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -59,22 +59,39 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
const void *data, size_t len)
{
struct blk_io_trace *t;
+ struct ring_buffer_event *event = NULL;
+ int pc = 0;
+ int cpu = smp_processor_id();
+ bool blk_tracer = blk_tracer_enabled;
+
+ if (blk_tracer) {
+ pc = preempt_count();
+ event = trace_buffer_lock_reserve(blk_tr, TRACE_BLK,
+ sizeof(*t) + len,
+ 0, pc);
+ if (!event)
+ return;
+ t = ring_buffer_event_data(event);
+ goto record_it;
+ }

if (!bt->rchan)
return;

t = relay_reserve(bt->rchan, sizeof(*t) + len);
if (t) {
- const int cpu = smp_processor_id();
-
t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
t->time = ktime_to_ns(ktime_get());
+record_it:
t->device = bt->dev;
t->action = action;
t->pid = pid;
t->cpu = cpu;
t->pdu_len = len;
memcpy((void *) t + sizeof(*t), data, len);
+
+ if (blk_tracer)
+ trace_buffer_unlock_commit(blk_tr, event, 0, pc);
}
}

@@ -110,14 +127,8 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
unsigned long flags;
char *buf;

- if (blk_tracer_enabled) {
- va_start(args, fmt);
- ftrace_vprintk(fmt, args);
- va_end(args);
- return;
- }
-
- if (!bt->msg_data)
+ if (unlikely(bt->trace_state != Blktrace_running &&
+ !blk_tracer_enabled))
return;

local_irq_save(flags);
@@ -168,9 +179,9 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
unsigned long *sequence;
pid_t pid;
int cpu, pc = 0;
+ bool blk_tracer = blk_tracer_enabled;

- if (unlikely(bt->trace_state != Blktrace_running &&
- !blk_tracer_enabled))
+ if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
return;

what |= ddir_act[rw & WRITE];
@@ -185,7 +196,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
return;
cpu = raw_smp_processor_id();

- if (blk_tracer_enabled) {
+ if (blk_tracer) {
tracing_record_cmdline(current);

pc = preempt_count();
@@ -235,7 +246,7 @@ record_it:
if (pdu_len)
memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);

- if (blk_tracer_enabled) {
+ if (blk_tracer) {
trace_buffer_unlock_commit(blk_tr, event, 0, pc);
return;
}
@@ -922,6 +933,11 @@ static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
int i = 0;
int tc = t->action >> BLK_TC_SHIFT;

+ if (t->action == BLK_TN_MESSAGE) {
+ rwbs[i++] = 'N';
+ goto out;
+ }
+
if (tc & BLK_TC_DISCARD)
rwbs[i++] = 'D';
else if (tc & BLK_TC_WRITE)
@@ -939,7 +955,7 @@ static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
rwbs[i++] = 'S';
if (tc & BLK_TC_META)
rwbs[i++] = 'M';
-
+out:
rwbs[i] = '\0';
}

@@ -1074,6 +1090,17 @@ static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
get_pdu_int(ent), cmd);
}

+static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
+{
+ int ret;
+ const struct blk_io_trace *t = te_blk_io_trace(ent);
+
+ ret = trace_seq_putmem(s, t + 1, t->pdu_len);
+ if (ret)
+ return trace_seq_putc(s, '\n');
+ return ret;
+}
+
/*
* struct tracer operations
*/
@@ -1146,6 +1173,13 @@ static enum print_line_t print_one_line(struct trace_iterator *iter,
long_act = !!(trace_flags & TRACE_ITER_VERBOSE);
log_action = classic ? &blk_log_action_classic : &blk_log_action;

+ if (t->action == BLK_TN_MESSAGE) {
+ ret = log_action(iter, long_act ? "message" : "m");
+ if (ret)
+ ret = blk_log_msg(s, iter->ent);
+ goto out;
+ }
+
if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
ret = trace_seq_printf(s, "Bad pc action %x\n", what);
else {
@@ -1153,7 +1187,7 @@ static enum print_line_t print_one_line(struct trace_iterator *iter,
if (ret)
ret = what2act[what].print(s, iter->ent);
}
-
+out:
return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
}

@@ -1253,11 +1287,16 @@ static int blk_trace_remove_queue(struct request_queue *q)
static int blk_trace_setup_queue(struct request_queue *q, dev_t dev)
{
struct blk_trace *old_bt, *bt = NULL;
+ int ret = -ENOMEM;

bt = kzalloc(sizeof(*bt), GFP_KERNEL);
if (!bt)
return -ENOMEM;

+ bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
+ if (!bt->msg_data)
+ goto free_bt;
+
bt->dev = dev;
bt->act_mask = (u16)-1;
bt->end_lba = -1ULL;
@@ -1265,14 +1304,17 @@ static int blk_trace_setup_queue(struct request_queue *q, dev_t dev)
old_bt = xchg(&q->blk_trace, bt);
if (old_bt != NULL) {
(void)xchg(&q->blk_trace, old_bt);
- kfree(bt);
- return -EBUSY;
+ ret = -EBUSY;
+ goto free_bt;
}

if (atomic_inc_return(&blk_probes_ref) == 1)
blk_register_tracepoints();
-
return 0;
+
+free_bt:
+ blk_trace_free(bt);
+ return ret;
}

/*

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