system: Add support for getting/setting i/o priorities and include a userspace tool

Signed-off-by: San Mehat <san@google.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/libcutils/iosched_policy.c b/libcutils/iosched_policy.c
new file mode 100644
index 0000000..4004a2a
--- /dev/null
+++ b/libcutils/iosched_policy.c
@@ -0,0 +1,61 @@
+
+/* libs/cutils/iosched_policy.c
+**
+** Copyright 2007, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License"); 
+** you may not use this file except in compliance with the License. 
+** You may obtain a copy of the License at 
+**
+**     http://www.apache.org/licenses/LICENSE-2.0 
+**
+** Unless required by applicable law or agreed to in writing, software 
+** distributed under the License is distributed on an "AS IS" BASIS, 
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
+** See the License for the specific language governing permissions and 
+** limitations under the License.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/unistd.h>
+
+#ifdef HAVE_SCHED_H
+
+#include <cutils/iosched_policy.h>
+
+extern int ioprio_set(int which, int who, int ioprio);
+
+enum {
+    WHO_PROCESS = 1,
+    WHO_PGRP,
+    WHO_USER,
+};
+
+#define CLASS_SHIFT 13
+#define IOPRIO_NORM 4
+
+int android_set_ioprio(int pid, IoSchedClass clazz, int ioprio) {
+    if (ioprio_set(WHO_PROCESS, pid, ioprio | (clazz << CLASS_SHIFT))) {
+        return -1;
+    }
+    return 0;
+}
+
+int android_get_ioprio(int pid, IoSchedClass *clazz, int *ioprio) {
+    int rc;
+
+    if ((rc = ioprio_get(WHO_PROCESS, pid)) < 0) {
+        return -1;
+    }
+
+    *clazz = (rc >> CLASS_SHIFT);
+    *ioprio = (rc & 0xff);
+    return 0;
+}
+
+#endif /* HAVE_SCHED_H */