[PATCH] binder: Use kmem_cache for binder_thread

Peikan Tsai
2019-08-29T05:50:00Z

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 <peikantsai@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