Merge "Add rss_hwm_reset binary" am: d1705920 am: 3d7d4504

// Copyright (C) 2018 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

//

//      https://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.

cc_binary {

    name: "rss_hwm_reset",

    srcs: [

        "rss_hwm_reset.cc",

    ],

    shared_libs: [

        "libbase",

        "liblog",

    ],

    init_rc: ["rss_hwm_reset.rc"],

}

/*

 * Copyright (C) 2018 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

 *

 *      https://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.

 */

 /*

  * rss_hwm_reset clears the RSS high-water mark counters for all currently

  * running processes. It writes "5" to /proc/PID/clear_refs for every PID.

  *

  * It runs in its own process becuase dac_override capability is required

  * in order to write to other processes' clear_refs.

  *

  * It is invoked from a system service by flipping sys.rss_hwm_reset.on

  * property to "1".

  */

#define LOG_TAG "rss_hwm_reset"

#include <dirent.h>

#include <string>

#include <android-base/file.h>

#include <android-base/stringprintf.h>

#include <log/log.h>

namespace {

// Resets RSS HWM counter for the selected process by writing 5 to

// /proc/PID/clear_refs.

void reset_rss_hwm(const char* pid) {

    std::string clear_refs_path =

            ::android::base::StringPrintf("/proc/%s/clear_refs", pid);

    ::android::base::WriteStringToFile("5", clear_refs_path);

}

}

// Clears RSS HWM counters for all currently running processes.

int main(int /* argc */, char** /* argv[] */) {

    DIR* dirp = opendir("/proc");

    if (dirp == nullptr) {

        ALOGE("unable to read /proc");

        return 1;

    }

    struct dirent* entry;

    while ((entry = readdir(dirp)) != nullptr) {

        // Skip entries that are not directories.

        if (entry->d_type != DT_DIR) continue;

        // Skip entries that do not contain only numbers.

        const char* pid = entry->d_name;

        while (*pid) {

            if (*pid < '0' || *pid > '9') break;

            pid++;

        }

        if (*pid != 0) continue;

        pid = entry->d_name;

        reset_rss_hwm(pid);

    }

    closedir(dirp);

    return 0;

}

# Copyright (C) 2018 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

#

#      https://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.

service rss_hwm_reset /system/bin/rss_hwm_reset

    class late_start

    disabled

    oneshot

    user nobody

    group nobody readproc

    writepid /dev/cpuset/system-background/tasks

    capabilities DAC_OVERRIDE

on property:sys.rss_hwm_reset.on=1

    start rss_hwm_reset

    setprop sys.rss_hwm_reset.on 0