[PATCH] binder: Use kmem_cache for binder_thread

[Peikan Tsai]

Hi,

The allocated size for each binder_thread is 512 bytes by kzalloc.
Because the size of binder_thread is fixed and it's only 304 bytes.
It will save 208 bytes per binder_thread when use create a kmem_cache
for the binder_thread.

Signed-off-by: Peikan Tsai <peikant...@gmail.com>
---
 drivers/android/binder.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index dc1c83eafc22..043e0ebd0fe7 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -87,6 +87,8 @@ static struct dentry *binder_debugfs_dir_entry_root;
 static struct dentry *binder_debugfs_dir_entry_proc;
 static atomic_t binder_last_id;

+static struct kmem_cache *binder_thread_cachep;
+
 static int proc_show(struct seq_file *m, void *unused);
 DEFINE_SHOW_ATTRIBUTE(proc);

@@ -4696,14 +4698,15 @@ static struct binder_thread *binder_get_thread(struct 
binder_proc *proc)
        thread = binder_get_thread_ilocked(proc, NULL);
        binder_inner_proc_unlock(proc);
        if (!thread) {
-               new_thread = kzalloc(sizeof(*thread), GFP_KERNEL);
+               new_thread = kmem_cache_zalloc(binder_thread_cachep,
+                                              GFP_KERNEL);
                if (new_thread == NULL)
                        return NULL;
                binder_inner_proc_lock(proc);
                thread = binder_get_thread_ilocked(proc, new_thread);
                binder_inner_proc_unlock(proc);
                if (thread != new_thread)
-                       kfree(new_thread);
+                       kmem_cache_free(binder_thread_cachep, new_thread);
        }
        return thread;
 }
@@ -4723,7 +4726,7 @@ static void binder_free_thread(struct binder_thread 
*thread)
        BUG_ON(!list_empty(&thread->todo));
        binder_stats_deleted(BINDER_STAT_THREAD);
        binder_proc_dec_tmpref(thread->proc);
-       kfree(thread);
+       kmem_cache_free(binder_thread_cachep, thread);
 }

 static int binder_thread_release(struct binder_proc *proc,
@@ -6095,6 +6098,12 @@ static int __init binder_init(void)
        if (ret)
                return ret;

+       binder_thread_cachep = kmem_cache_create("binder_thread",
+                                                sizeof(struct binder_thread),
+                                                0, 0, NULL);
+       if (!binder_thread_cachep)
+               return -ENOMEM;
+
        atomic_set(&binder_transaction_log.cur, ~0U);
        atomic_set(&binder_transaction_log_failed.cur, ~0U);

@@ -6167,6 +6176,7 @@ static int __init binder_init(void)

 err_alloc_device_names_failed:
        debugfs_remove_recursive(binder_debugfs_dir_entry_root);
+       kmem_cache_destroy(binder_thread_cachep);

        return ret;
 }
--
2.17.1

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