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Subject[tip:tracing/core] blktrace: fix output of BLK_TC_PC events
Commit-ID:  66de7792c02693b49671afe58c771fde3b092fc7
Gitweb: http://git.kernel.org/tip/66de7792c02693b49671afe58c771fde3b092fc7
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Wed, 1 Apr 2009 16:19:19 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Sun, 12 Apr 2009 15:32:46 +0200

blktrace: fix output of BLK_TC_PC events

BLK_TC_PC events should be treated differently with BLK_TC_FS events.

Before this patch:

# echo 1 > /sys/block/sda/sda1/trace/enable
# echo pc > /sys/block/sda/sda1/trace/act_mask
# echo blk > /debugfs/tracing/current_tracer
# (generate some BLK_TC_PC events)
# cat trace
bash-2184 [000] 1774.275413: 8,7 I N [bash]
bash-2184 [000] 1774.275435: 8,7 D N [bash]
bash-2184 [000] 1774.275540: 8,7 I R [bash]
bash-2184 [000] 1774.275547: 8,7 D R [bash]
ksoftirqd/0-4 [000] 1774.275580: 8,7 C N 0 [0]
bash-2184 [000] 1774.275648: 8,7 I R [bash]
bash-2184 [000] 1774.275653: 8,7 D R [bash]
ksoftirqd/0-4 [000] 1774.275682: 8,7 C N 0 [0]
bash-2184 [000] 1774.275739: 8,7 I R [bash]
bash-2184 [000] 1774.275744: 8,7 D R [bash]
ksoftirqd/0-4 [000] 1774.275771: 8,7 C N 0 [0]
bash-2184 [000] 1774.275804: 8,7 I R [bash]
bash-2184 [000] 1774.275808: 8,7 D R [bash]
ksoftirqd/0-4 [000] 1774.275836: 8,7 C N 0 [0]
After this patch:

# cat trace
bash-2263 [000] 366.782149: 8,7 I N 0 (00 ..) [bash]
bash-2263 [000] 366.782323: 8,7 D N 0 (00 ..) [bash]
bash-2263 [000] 366.782557: 8,7 I R 8 (25 00 ..) [bash]
bash-2263 [000] 366.782560: 8,7 D R 8 (25 00 ..) [bash]
ksoftirqd/0-4 [000] 366.782582: 8,7 C N (25 00 ..) [0]
bash-2263 [000] 366.782648: 8,7 I R 8 (5a 00 3f 00) [bash]
bash-2263 [000] 366.782650: 8,7 D R 8 (5a 00 3f 00) [bash]
ksoftirqd/0-4 [000] 366.782669: 8,7 C N (5a 00 3f 00) [0]
bash-2263 [000] 366.782710: 8,7 I R 8 (5a 00 08 00) [bash]
bash-2263 [000] 366.782713: 8,7 D R 8 (5a 00 08 00) [bash]
ksoftirqd/0-4 [000] 366.782730: 8,7 C N (5a 00 08 00) [0]
bash-2263 [000] 366.783375: 8,7 I R 36 (5a 00 08 00) [bash]
bash-2263 [000] 366.783379: 8,7 D R 36 (5a 00 08 00) [bash]
ksoftirqd/0-4 [000] 366.783404: 8,7 C N (5a 00 08 00) [0]

This is what we do with PC events in user-space blktrace.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49D32387.9040106@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
kernel/trace/blktrace.c | 88 ++++++++++++++++++++++++++++++++++++++++++----
1 files changed, 80 insertions(+), 8 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index e45e1af..2b98195 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -971,6 +971,16 @@ static inline const void *pdu_start(const struct trace_entry *ent)
return te_blk_io_trace(ent) + 1;
}

+static inline u32 t_action(const struct trace_entry *ent)
+{
+ return te_blk_io_trace(ent)->action;
+}
+
+static inline u32 t_bytes(const struct trace_entry *ent)
+{
+ return te_blk_io_trace(ent)->bytes;
+}
+
static inline u32 t_sec(const struct trace_entry *ent)
{
return te_blk_io_trace(ent)->bytes >> 9;
@@ -1031,25 +1041,87 @@ static int blk_log_action(struct trace_iterator *iter, const char *act)
MAJOR(t->device), MINOR(t->device), act, rwbs);
}

+static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
+{
+ const char *pdu_buf;
+ int pdu_len;
+ int i, end, ret;
+
+ pdu_buf = pdu_start(ent);
+ pdu_len = te_blk_io_trace(ent)->pdu_len;
+
+ if (!pdu_len)
+ return 1;
+
+ /* find the last zero that needs to be printed */
+ for (end = pdu_len - 1; end >= 0; end--)
+ if (pdu_buf[end])
+ break;
+ end++;
+
+ if (!trace_seq_putc(s, '('))
+ return 0;
+
+ for (i = 0; i < pdu_len; i++) {
+
+ ret = trace_seq_printf(s, "%s%02x",
+ i == 0 ? "" : " ", pdu_buf[i]);
+ if (!ret)
+ return ret;
+
+ /*
+ * stop when the rest is just zeroes and indicate so
+ * with a ".." appended
+ */
+ if (i == end && end != pdu_len - 1)
+ return trace_seq_puts(s, " ..) ");
+ }
+
+ return trace_seq_puts(s, ") ");
+}
+
static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
{
char cmd[TASK_COMM_LEN];

trace_find_cmdline(ent->pid, cmd);

- if (t_sec(ent))
- return trace_seq_printf(s, "%llu + %u [%s]\n",
- t_sector(ent), t_sec(ent), cmd);
- return trace_seq_printf(s, "[%s]\n", cmd);
+ if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
+ int ret;
+
+ ret = trace_seq_printf(s, "%u ", t_bytes(ent));
+ if (!ret)
+ return 0;
+ ret = blk_log_dump_pdu(s, ent);
+ if (!ret)
+ return 0;
+ return trace_seq_printf(s, "[%s]\n", cmd);
+ } else {
+ if (t_sec(ent))
+ return trace_seq_printf(s, "%llu + %u [%s]\n",
+ t_sector(ent), t_sec(ent), cmd);
+ return trace_seq_printf(s, "[%s]\n", cmd);
+ }
}

static int blk_log_with_error(struct trace_seq *s,
const struct trace_entry *ent)
{
- if (t_sec(ent))
- return trace_seq_printf(s, "%llu + %u [%d]\n", t_sector(ent),
- t_sec(ent), t_error(ent));
- return trace_seq_printf(s, "%llu [%d]\n", t_sector(ent), t_error(ent));
+ if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
+ int ret;
+
+ ret = blk_log_dump_pdu(s, ent);
+ if (ret)
+ return trace_seq_printf(s, "[%d]\n", t_error(ent));
+ return 0;
+ } else {
+ if (t_sec(ent))
+ return trace_seq_printf(s, "%llu + %u [%d]\n",
+ t_sector(ent),
+ t_sec(ent), t_error(ent));
+ return trace_seq_printf(s, "%llu [%d]\n",
+ t_sector(ent), t_error(ent));
+ }
}

static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)

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