io-threads: Support mem-pool allocator for iot_request_t

This commit brings in support for allocation of iot_request_t's
in io-threads through the use of the mem-pool. We're hoping
that the overheads of hundreds and thousands of small allocations
can be avoided through this.

The important point to note is that the memory pool is not
for the translator as a whole but there is one small memory
pool for each worker thread. Not only does that help us
avoid malloc overheads for small allocations like iot_request_t
but also avoid contention on the heap data structures when multiple
threads want an iot_request_t from the pool.

Signed-off-by: Anand V. Avati <avati@dev.gluster.com>

1 files changed, 29 insertions, 23 deletions

diff --git a/xlators/performance/io-threads/src/io-threads.c b/xlators/performance/io-threads/src/io-threads.c
index 813b7d73d..a0d5d97df 100644
--- a/xlators/performance/io-threads/src/io-threads.c
+++ b/xlators/performance/io-threads/src/io-threads.c
@@ -44,7 +44,7 @@ void
 _iot_queue (iot_worker_t *worker, iot_request_t *req);
 
 iot_request_t *
-iot_init_request (call_stub_t *stub);
+iot_init_request (iot_worker_t *conf, call_stub_t *stub);
 
 int
 iot_startup_workers (iot_worker_t **workers, int start_idx, int count,
@@ -60,7 +60,7 @@ int
 iot_startup_worker (iot_worker_t *worker, iot_worker_fn workerfunc);
 
 void
-iot_destroy_request (iot_request_t * req);
+iot_destroy_request (iot_worker_t *worker, iot_request_t * req);
 
 
 /* I know this function modularizes things a bit too much,
@@ -129,7 +129,7 @@ iot_schedule_unordered (iot_conf_t *conf, inode_t *inode, call_stub_t *stub)
         idx = iot_unordered_request_balancer (conf);
         selected_worker = conf->uworkers[idx];
 
-        req = iot_init_request (stub);
+        req = iot_init_request (selected_worker, stub);
         if (req == NULL) {
                 ret = -ENOMEM;
                 goto out;
@@ -138,7 +138,7 @@ iot_schedule_unordered (iot_conf_t *conf, inode_t *inode, call_stub_t *stub)
         ret = iot_request_queue_and_thread_fire (selected_worker,
                                                  iot_worker_unordered, req);
         if (ret < 0) {
-                iot_destroy_request (req);
+                iot_destroy_request (selected_worker, req);
         }
 out:
         return ret;
@@ -214,14 +214,6 @@ iot_schedule_ordered (iot_conf_t *conf, inode_t *inode, call_stub_t *stub)
                 goto out;
         }
 
-        req = iot_init_request (stub);
-        if (req == NULL) {
-                gf_log (conf->this->name, GF_LOG_ERROR,
-                        "out of memory");
-                ret = -ENOMEM;
-                goto out;
-        }
-
         LOCK (&inode->lock);
         {
                 balstatus = iot_ordered_request_balancer (conf, inode, &idx);
@@ -238,6 +230,14 @@ iot_schedule_ordered (iot_conf_t *conf, inode_t *inode, call_stub_t *stub)
                  * added the request to the worker queue.
                  */
                 selected_worker = conf->oworkers[idx];
+
+                req = iot_init_request (selected_worker, stub);
+                if (req == NULL) {
+                        gf_log (conf->this->name, GF_LOG_ERROR,"out of memory");
+                        ret = -ENOMEM;
+                        goto unlock_out;
+                }
+
                 ret = iot_request_queue_and_thread_fire (selected_worker,
                                                          iot_worker_ordered,
                                                          req);
@@ -248,7 +248,7 @@ unlock_out:
 out:
         if (ret < 0) {
                 if (req != NULL) {
-                        iot_destroy_request (req);
+                        iot_destroy_request (selected_worker, req);
                 }
         }
         return ret;
@@ -2234,11 +2234,11 @@ _iot_queue (iot_worker_t *worker, iot_request_t *req)
 
 
 iot_request_t *
-iot_init_request (call_stub_t *stub)
+iot_init_request (iot_worker_t *worker, call_stub_t *stub)
 {
 	iot_request_t   *req = NULL;
 
-        req = CALLOC (1, sizeof (iot_request_t));
+        req = mem_get (worker->req_pool);
         if (req == NULL) {
                 goto out;
         }
@@ -2250,12 +2250,12 @@ out:
 
 
 void
-iot_destroy_request (iot_request_t * req)
+iot_destroy_request (iot_worker_t *worker, iot_request_t * req)
 {
-        if (req == NULL)
+        if ((req == NULL) || (worker == NULL))
                 return;
 
-        FREE (req);
+        mem_put (worker->req_pool, req);
 }
 
 
@@ -2356,8 +2356,7 @@ iot_dequeue_ordered (iot_worker_t *worker)
         }
 out:
 	pthread_mutex_unlock (&worker->qlock);
-
-	FREE (req);
+        iot_destroy_request (worker, req);
 
 	return stub;
 }
@@ -2482,8 +2481,7 @@ iot_dequeue_unordered (iot_worker_t *worker)
         }
 out:
 	pthread_mutex_unlock (&worker->qlock);
-
-	FREE (req);
+        iot_destroy_request (worker, req);
 
 	return stub;
 }
@@ -2526,7 +2524,7 @@ deallocate_workers (iot_worker_t **workers,
         end_count = count + start_alloc_idx;
         for (i = start_alloc_idx; (i < end_count); i++) {
                 if (workers[i] != NULL) {
-                        free (workers[i]);
+                        FREE (workers[i]);
                         workers[i] = NULL;
                 }
         }
@@ -2556,6 +2554,10 @@ allocate_worker (iot_conf_t * conf)
                 goto out;
         }
 
+        wrk->req_pool = mem_pool_new (iot_request_t, IOT_REQUEST_MEMPOOL_SIZE);
+        if (wrk->req_pool == NULL)
+                goto free_wrk;
+
         INIT_LIST_HEAD (&wrk->rqlist);
         wrk->conf = conf;
         pthread_cond_init (&wrk->dq_cond, NULL);
@@ -2564,6 +2566,10 @@ allocate_worker (iot_conf_t * conf)
 
 out:
         return wrk;
+
+free_wrk:
+        FREE (wrk);
+        return NULL;
 }