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Subject[PATCH 1/3] tracing/stat: sort in ascending order
Currently the output of trace_stat/workqueues is totally reversed:

# cat /debug/tracing/trace_stat/workqueues
...
1 17 17 210 37 `-blk_unplug_work+0x0/0x57
1 3779 3779 181 11 |-cfq_kick_queue+0x0/0x2f
1 3796 3796 kblockd/1:120
...
The correct output should be:

1 3796 3796 kblockd/1:120
1 3779 3779 181 11 |-cfq_kick_queue+0x0/0x2f
1 17 17 210 37 `-blk_unplug_work+0x0/0x57
It's caused by "tracing/stat: replace linked list by an rbtree for sorting"
(53059c9b67a62a3dc8c80204d3da42b9267ea5a0).

Though we can simply change dummy_cmp() to return -1 instead of 1, IMO
it's better to always do ascending sorting in trace_stat.c, and leave each
stat tracer to decide whether to sort in descending or ascending order.

[ Impact: fix the output of trace_stat/workqueue ]

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
kernel/trace/ftrace.c | 12 ++++++------
kernel/trace/trace_branch.c | 5 +++--
kernel/trace/trace_stat.c | 6 +-----
3 files changed, 10 insertions(+), 13 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 140699a..3dd16bd 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -315,29 +315,29 @@ static void *function_stat_start(struct tracer_stat *trace)
}

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-/* function graph compares on total time */
+/* function graph compares on total time in reverse order */
static int function_stat_cmp(void *p1, void *p2)
{
struct ftrace_profile *a = p1;
struct ftrace_profile *b = p2;

- if (a->time < b->time)
- return -1;
if (a->time > b->time)
+ return -1;
+ if (a->time < b->time)
return 1;
else
return 0;
}
#else
-/* not function graph compares against hits */
+/* not function graph compares against hits in reverse order */
static int function_stat_cmp(void *p1, void *p2)
{
struct ftrace_profile *a = p1;
struct ftrace_profile *b = p2;

- if (a->counter < b->counter)
- return -1;
if (a->counter > b->counter)
+ return -1;
+ if (a->counter < b->counter)
return 1;
else
return 0;
diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index 7a7a9fd..df58411 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -301,9 +301,10 @@ static int annotated_branch_stat_cmp(void *p1, void *p2)
percent_a = get_incorrect_percent(a);
percent_b = get_incorrect_percent(b);

- if (percent_a < percent_b)
- return -1;
+ /* sort in descending order */
if (percent_a > percent_b)
+ return -1;
+ if (percent_a < percent_b)
return 1;
else
return 0;
diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
index 2e849b5..6efbcb4 100644
--- a/kernel/trace/trace_stat.c
+++ b/kernel/trace/trace_stat.c
@@ -98,10 +98,6 @@ insert_stat(struct rb_root *root, struct stat_node *data, cmp_stat_t cmp)
{
struct rb_node **new = &(root->rb_node), *parent = NULL;

- /*
- * Figure out where to put new node
- * This is a descendent sorting
- */
while (*new) {
struct stat_node *this;
int result;
@@ -110,7 +106,7 @@ insert_stat(struct rb_root *root, struct stat_node *data, cmp_stat_t cmp)
result = cmp(data->stat, this->stat);

parent = *new;
- if (result >= 0)
+ if (result < 0)
new = &((*new)->rb_left);
else
new = &((*new)->rb_right);
--
1.5.4.rc3


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