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Subject[PATCH v2 3/3] ftrace: Get rid of ftrace_profile_bits
Date
From: Namhyung Kim <namhyung.kim@lge.com>

It seems that function profiler's hash size is fixed at 1024. Add and
use FTRACE_PROFILE_HASH_BITS instead and update hash size macro.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
kernel/trace/ftrace.c | 15 ++++-----------
1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d38ad7145f2f..78f4398cb608 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -486,7 +486,6 @@ struct ftrace_profile_stat {
#define PROFILES_PER_PAGE \
(PROFILE_RECORDS_SIZE / sizeof(struct ftrace_profile))

-static int ftrace_profile_bits __read_mostly;
static int ftrace_profile_enabled __read_mostly;

/* ftrace_profile_lock - synchronize the enable and disable of the profiler */
@@ -494,7 +493,8 @@ static DEFINE_MUTEX(ftrace_profile_lock);

static DEFINE_PER_CPU(struct ftrace_profile_stat, ftrace_profile_stats);

-#define FTRACE_PROFILE_HASH_SIZE 1024 /* must be power of 2 */
+#define FTRACE_PROFILE_HASH_BITS 10
+#define FTRACE_PROFILE_HASH_SIZE (1 << FTRACE_PROFILE_HASH_BITS)

static void *
function_stat_next(void *v, int idx)
@@ -724,13 +724,6 @@ static int ftrace_profile_init_cpu(int cpu)
if (!stat->hash)
return -ENOMEM;

- if (!ftrace_profile_bits) {
- size--;
-
- for (; size; size >>= 1)
- ftrace_profile_bits++;
- }
-
/* Preallocate the function profiling pages */
if (ftrace_profile_pages_init(stat) < 0) {
kfree(stat->hash);
@@ -764,7 +757,7 @@ ftrace_find_profiled_func(struct ftrace_profile_stat *stat, unsigned long ip)
struct hlist_node *n;
unsigned long key;

- key = hash_long(ip, ftrace_profile_bits);
+ key = hash_long(ip, FTRACE_PROFILE_HASH_BITS);
hhd = &stat->hash[key];

if (hlist_empty(hhd))
@@ -783,7 +776,7 @@ static void ftrace_add_profile(struct ftrace_profile_stat *stat,
{
unsigned long key;

- key = hash_long(rec->ip, ftrace_profile_bits);
+ key = hash_long(rec->ip, FTRACE_PROFILE_HASH_BITS);
hlist_add_head_rcu(&rec->node, &stat->hash[key]);
}

--
1.7.11.7


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