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/*
** Copyright 2007-2014, The Android Open Source Project
** Copyright 2015, The CyanogenMod 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 <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <cutils/iosched_policy.h>
#define LOG_TAG "iosched_policy"
#include <cutils/log.h>
#define __android_unused __attribute__((__unused__))
#ifdef HAVE_ANDROID_OS
#include <linux/ioprio.h>
#include <sys/syscall.h>
#include <sys/stat.h>
static int __rtio_cgroup_supported = -1;
static pthread_once_t __rtio_init_once = PTHREAD_ONCE_INIT;
int android_set_ioprio(int pid __android_unused, IoSchedClass clazz __android_unused, int ioprio __android_unused) {
if (syscall(SYS_ioprio_set, IOPRIO_WHO_PROCESS, pid, ioprio | (clazz << IOPRIO_CLASS_SHIFT))) {
return -1;
}
return 0;
}
int android_get_ioprio(int pid __android_unused, IoSchedClass *clazz, int *ioprio) {
int rc;
if ((rc = syscall(SYS_ioprio_get, IOPRIO_WHO_PROCESS, pid)) < 0) {
return -1;
}
*clazz = (rc >> IOPRIO_CLASS_SHIFT);
*ioprio = (rc & 0xff);
return 0;
}
static void __initialize_rtio(void) {
if (!access("/sys/fs/cgroup/bfqio/tasks", W_OK) ||
!access("/sys/fs/cgroup/bfqio/rt-display/tasks", W_OK)) {
__rtio_cgroup_supported = 1;
} else {
__rtio_cgroup_supported = 0;
}
}
int android_set_rt_ioprio(int tid, int rt) {
int fd = -1, rc = -1;
pthread_once(&__rtio_init_once, __initialize_rtio);
if (__rtio_cgroup_supported != 1) {
return -1;
}
if (rt) {
fd = open("/sys/fs/cgroup/bfqio/rt-display/tasks", O_WRONLY | O_CLOEXEC);
} else {
fd = open("/sys/fs/cgroup/bfqio/tasks", O_WRONLY | O_CLOEXEC);
}
if (fd < 0) {
return -1;
}
#ifdef HAVE_GETTID
if (tid == 0) {
tid = gettid();
}
#endif
// specialized itoa -- works for tid > 0
char text[22];
char *end = text + sizeof(text) - 1;
char *ptr = end;
*ptr = '\0';
while (tid > 0) {
*--ptr = '0' + (tid % 10);
tid = tid / 10;
}
rc = write(fd, ptr, end - ptr);
if (rc < 0) {
/*
* If the thread is in the process of exiting,
* don't flag an error
*/
if (errno == ESRCH) {
rc = 0;
} else {
SLOGV("android_set_rt_ioprio failed to write '%s' (%s); fd=%d\n",
ptr, strerror(errno), fd);
}
}
close(fd);
return rc;
}
#else
int android_set_ioprio(int pid __android_unused, IoSchedClass clazz __android_unused, int ioprio __android_unused) {
return 0;
}
int android_get_ioprio(int pid __android_unused, IoSchedClass *clazz, int *ioprio) {
*clazz = IoSchedClass_NONE;
*ioprio = 0;
return 0;
}
int android_set_rt_ioprio(int tid __android_unused, int rt __android_unused)
{
return 0;
}
#endif
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