73 lines
2.2 KiB
C++
73 lines
2.2 KiB
C++
/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* rss_hwm_reset clears the RSS high-water mark counters for all currently
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* running processes. It writes "5" to /proc/PID/clear_refs for every PID.
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*
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* It runs in its own process becuase dac_override capability is required
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* in order to write to other processes' clear_refs.
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*
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* It is invoked from a system service by flipping sys.rss_hwm_reset.on
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* property to "1".
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*/
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#define LOG_TAG "rss_hwm_reset"
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#include <dirent.h>
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#include <string>
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#include <android-base/file.h>
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#include <android-base/stringprintf.h>
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#include <log/log.h>
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namespace {
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// Resets RSS HWM counter for the selected process by writing 5 to
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// /proc/PID/clear_refs.
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void reset_rss_hwm(const char* pid) {
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std::string clear_refs_path =
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::android::base::StringPrintf("/proc/%s/clear_refs", pid);
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::android::base::WriteStringToFile("5", clear_refs_path);
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}
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}
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// Clears RSS HWM counters for all currently running processes.
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int main(int /* argc */, char** /* argv[] */) {
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DIR* dirp = opendir("/proc");
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if (dirp == nullptr) {
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ALOGE("unable to read /proc");
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return 1;
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}
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struct dirent* entry;
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while ((entry = readdir(dirp)) != nullptr) {
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// Skip entries that are not directories.
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if (entry->d_type != DT_DIR) continue;
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// Skip entries that do not contain only numbers.
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const char* pid = entry->d_name;
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while (*pid) {
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if (*pid < '0' || *pid > '9') break;
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pid++;
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}
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if (*pid != 0) continue;
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pid = entry->d_name;
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reset_rss_hwm(pid);
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}
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closedir(dirp);
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return 0;
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}
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