[PATCH] Add ioscheduler=x option to allow setting io scheduler

[fio.git] / fio.c

diff --git a/fio.c b/fio.c
index 79c11d5cdcee503d879c510e8e57036df421d895..bd938979f61caa3f59152d50c4eee03b24b84c53 100644 (file)
--- a/fio.c
+++ b/fio.c
@@ -1787,9 +1787,58 @@ static void init_disk_util(struct thread_data *td)
                sprintf(foo, "%s", p);
        }
 
+       td->sysfs_root = strdup(foo);
        disk_util_add(dev, foo);
 }
 
+static int switch_ioscheduler(struct thread_data *td)
+{
+       char tmp[256], tmp2[128];
+       FILE *f;
+       int ret;
+
+       sprintf(tmp, "%s/queue/scheduler", td->sysfs_root);
+
+       f = fopen(tmp, "r+");
+       if (!f) {
+               td_verror(td, errno);
+               return 1;
+       }
+
+       /*
+        * Set io scheduler.
+        */
+       ret = fwrite(td->ioscheduler, strlen(td->ioscheduler), 1, f);
+       if (ferror(f) || ret != 1) {
+               td_verror(td, errno);
+               fclose(f);
+               return 1;
+       }
+
+       rewind(f);
+
+       /*
+        * Read back and check that the selected scheduler is now the default.
+        */
+       ret = fread(tmp, 1, sizeof(tmp), f);
+       if (ferror(f) || ret < 0) {
+               td_verror(td, errno);
+               fclose(f);
+               return 1;
+       }
+
+       sprintf(tmp2, "[%s]", td->ioscheduler);
+       if (!strstr(tmp, tmp2)) {
+               fprintf(stderr, "fio: io scheduler %s not found\n", td->ioscheduler);
+               td_verror(td, EINVAL);
+               fclose(f);
+               return 1;
+       }
+
+       fclose(f);
+       return 0;
+}
+
 static void disk_util_timer_arm(void)
 {
        itimer.it_value.tv_sec = 0;
@@ -1869,6 +1918,9 @@ static void *thread_main(void *data)
        if (init_random_state(td))
                goto err;
 
+       if (td->ioscheduler && switch_ioscheduler(td))
+               goto err;
+
        td_set_runstate(td, TD_INITIALIZED);
        sem_post(&startup_sem);
        sem_wait(&td->mutex);
@@ -1946,6 +1998,10 @@ err:
                free(td->exec_prerun);
        if (td->exec_postrun)
                free(td->exec_postrun);
+       if (td->ioscheduler)
+               free(td->ioscheduler);
+       if (td->sysfs_root)
+               free(td->sysfs_root);
        cleanup_io(td);
        cleanup_io_u(td);
        td_set_runstate(td, TD_EXITED);