Added a 'hack' to enable/disable PRIO based on the user preference on…

… how many IOs (percentage) should be of higher priority.

engines/libaio.c

@@ -41,6 +41,8 @@ struct libaio_data {
 struct libaio_options {
 	void *pad;
 	unsigned int userspace_reap;
+    unsigned int prio_percent; 
+    unsigned int prio_io_count;
 };
 
 static struct fio_option options[] = {
@@ -53,6 +55,17 @@ static struct fio_option options[] = {
 		.category = FIO_OPT_C_ENGINE,
 		.group	= FIO_OPT_G_LIBAIO,
 	},
+	{
+		.name	= "prio_percent",
+		.lname	= "prio percentage",
+		.type	= FIO_OPT_INT,
+		.off1	= offsetof(struct libaio_options, prio_percent),
+		.minval	= 1,
+		.maxval	= 100,
+		.help	= "Split the prioclass setting for IO",
+		.category = FIO_OPT_C_ENGINE,
+		.group	= FIO_OPT_G_LIBAIO,
+	},
 	{
 		.name	= NULL,
 	},
@@ -241,6 +254,8 @@ static int fio_libaio_commit(struct thread_data *td)
 	struct libaio_data *ld = td->io_ops_data;
 	struct iocb **iocbs;
 	struct io_u **io_us;
+    struct thread_options *o = &td->o;
+	struct libaio_options *eo = td->eo;
 	struct timeval tv;
 	int ret, wait_start = 0;
 
@@ -254,6 +269,22 @@ static int fio_libaio_commit(struct thread_data *td)
 		io_us = ld->io_us + ld->tail;
 		iocbs = ld->iocbs + ld->tail;
 
+        if (fio_option_is_set(o, ioprio) ||
+            fio_option_is_set(o, ioprio_class)) {
+
+            if (eo->prio_percent) {
+                if ((++eo->prio_io_count  % 100/eo->prio_percent) == 0) {
+                    dprint(FD_IO, "Enable PRIO \n");
+                    ioprio_set(IOPRIO_WHO_PROCESS, 0, o->ioprio_class, o->ioprio);
+                }
+                else
+                {
+                    dprint(FD_IO, "Disable PRIO \n");
+                    ioprio_set(IOPRIO_WHO_PROCESS, 0, 0, 0);
+                } 
+            }
+        }
+
 		ret = io_submit(ld->aio_ctx, nr, iocbs);
 		if (ret > 0) {
 			fio_libaio_queued(td, io_us, ret);
@@ -363,6 +394,8 @@ static int fio_libaio_init(struct thread_data *td)
 	ld->iocbs = calloc(ld->entries, sizeof(struct iocb *));
 	ld->io_us = calloc(ld->entries, sizeof(struct io_u *));
 
+    o->prio_io_count = 0;
+
 	td->io_ops_data = ld;
 	return 0;
 }