[PATCH 05/11] ftrace: create memcache for hash entries

[Changbin Du]

When CONFIG_FTRACE_FUNC_PROTOTYPE is enabled, thousands of
ftrace_func_entry instances are created. So create a dedicated
memcache to enhance performance.

Signed-off-by: Changbin Du <changbin...@gmail.com>
---
 kernel/trace/ftrace.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a314f0768b2c..cfcb8dad93ea 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -94,6 +94,8 @@ struct ftrace_ops *function_trace_op __read_mostly = 
&ftrace_list_end;
 /* What to set function_trace_op to */
 static struct ftrace_ops *set_function_trace_op;
 
+struct kmem_cache *hash_entry_cache;
+
 static bool ftrace_pids_enabled(struct ftrace_ops *ops)
 {
        struct trace_array *tr;
@@ -1169,7 +1171,7 @@ static int add_hash_entry(struct ftrace_hash *hash, 
unsigned long ip,
 {
        struct ftrace_func_entry *entry;
 
-       entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+       entry = kmem_cache_alloc(hash_entry_cache, GFP_KERNEL);
        if (!entry)
                return -ENOMEM;
 
@@ -6153,6 +6155,15 @@ void __init ftrace_init(void)
        if (ret)
                goto failed;
 
+       hash_entry_cache = kmem_cache_create("ftrace-hash",
+                                            sizeof(struct ftrace_func_entry),
+                                            sizeof(struct ftrace_func_entry),
+                                            0, NULL);
+       if (!hash_entry_cache) {
+               pr_err("failed to create ftrace hash entry cache\n");
+               goto failed;
+       }
+
        count = __stop_mcount_loc - __start_mcount_loc;
        if (!count) {
                pr_info("ftrace: No functions to be traced?\n");
@@ -6172,6 +6183,10 @@ void __init ftrace_init(void)
 
        return;
  failed:
+       if (hash_entry_cache) {
+               kmem_cache_destroy(hash_entry_cache);
+               hash_entry_cache = NULL;
+       }
        ftrace_disabled = 1;
 }
 
-- 
2.20.1