[PATCH] rcuperf: Add support to vary the slab object sizes

[Joel Fernandes]

Signed-off-by: Joel Fernandes <joelaf@xxxxxxxxxx>
---
 kernel/rcu/rcuperf.c | 43 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 36 insertions(+), 7 deletions(-)

diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index a4a8d097d84d..216d7c072ca2 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -600,17 +600,29 @@ static int kfree_nrealthreads;
 static atomic_t n_kfree_perf_thread_started;
 static atomic_t n_kfree_perf_thread_ended;
 
-struct kfree_obj {
-	char kfree_obj[8];
-	struct rcu_head rh;
-};
+/*
+ * Define a kfree_obj with size as the @size parameter + the size of rcu_head
+ * (rcu_head is 16 bytes on 64-bit arch).
+ */
+#define DEFINE_KFREE_OBJ(size)	\
+struct kfree_obj_ ## size {	\
+	char kfree_obj[size];	\
+	struct rcu_head rh;	\
+}
+
+/* This should goto the right sized slabs on both 32-bit and 64-bit arch */
+DEFINE_KFREE_OBJ(16); // goes on kmalloc-32 slab
+DEFINE_KFREE_OBJ(32); // goes on kmalloc-64 slab
+DEFINE_KFREE_OBJ(64); // goes on kmalloc-96 slab
+DEFINE_KFREE_OBJ(96); // goes on kmalloc-128 slab
 
 static int
 kfree_perf_thread(void *arg)
 {
 	int i, loop = 0;
 	long me = (long)arg;
-	struct kfree_obj *alloc_ptr;
+	void *alloc_ptr;
+
 	u64 start_time, end_time;
 	long long mem_begin, mem_during = 0;
 
@@ -635,11 +647,28 @@ kfree_perf_thread(void *arg)
 		}
 
 		for (i = 0; i < kfree_alloc_num; i++) {
-			alloc_ptr = kmalloc(sizeof(struct kfree_obj), GFP_KERNEL);
+			int kfree_type = i % 4;
+
+			if (kfree_type == 0)
+				alloc_ptr = kmalloc(sizeof(struct kfree_obj_16), GFP_KERNEL);
+			else if (kfree_type == 1)
+				alloc_ptr = kmalloc(sizeof(struct kfree_obj_32), GFP_KERNEL);
+			else if (kfree_type == 2)
+				alloc_ptr = kmalloc(sizeof(struct kfree_obj_64), GFP_KERNEL);
+			else
+				alloc_ptr = kmalloc(sizeof(struct kfree_obj_96),  GFP_KERNEL);
+
 			if (!alloc_ptr)
 				return -ENOMEM;
 
-			kfree_rcu(alloc_ptr, rh);
+			if (kfree_type == 0)
+				kfree_rcu((struct kfree_obj_16 *)alloc_ptr, rh);
+			else if (kfree_type == 1)
+				kfree_rcu((struct kfree_obj_32 *)alloc_ptr, rh);
+			else if (kfree_type == 2)
+				kfree_rcu((struct kfree_obj_64 *)alloc_ptr, rh);
+			else
+				kfree_rcu((struct kfree_obj_96 *)alloc_ptr, rh);
 		}
 
 		cond_resched();
-- 
2.25.0.rc1.283.g88dfdc4193-goog