iosched_policy.c revision 10d469bff9031e857c7a290dae7d6ccf7b3a18f8 
1
2/* libs/cutils/iosched_policy.c
3**
4** Copyright 2007, The Android Open Source Project
5**
6** Licensed under the Apache License, Version 2.0 (the "License");
7** you may not use this file except in compliance with the License.
8** You may obtain a copy of the License at
9**
10**     http://www.apache.org/licenses/LICENSE-2.0
11**
12** Unless required by applicable law or agreed to in writing, software
13** distributed under the License is distributed on an "AS IS" BASIS,
14** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15** See the License for the specific language governing permissions and
16** limitations under the License.
17*/
18
19#include <stdio.h>
20#include <stdlib.h>
21#include <unistd.h>
22#include <string.h>
23#include <errno.h>
24#include <fcntl.h>
25#include <linux/unistd.h>
26
27#ifdef HAVE_SCHED_H
28
29#include <cutils/iosched_policy.h>
30
31extern int ioprio_set(int which, int who, int ioprio);
32
33enum {
34    WHO_PROCESS = 1,
35    WHO_PGRP,
36    WHO_USER,
37};
38
39#define CLASS_SHIFT 13
40#define IOPRIO_NORM 4
41
42int android_set_ioprio(int pid, IoSchedClass clazz, int ioprio) {
43    if (ioprio_set(WHO_PROCESS, pid, ioprio | (clazz << CLASS_SHIFT))) {
44        return -1;
45    }
46    return 0;
47}
48
49int android_get_ioprio(int pid, IoSchedClass *clazz, int *ioprio) {
50    int rc;
51
52    if ((rc = ioprio_get(WHO_PROCESS, pid)) < 0) {
53        return -1;
54    }
55
56    *clazz = (rc >> CLASS_SHIFT);
57    *ioprio = (rc & 0xff);
58    return 0;
59}
60
61#endif /* HAVE_SCHED_H */
62