Add rss_hwm_reset binary
rss_hwm_reset is binary that reset RSS high-water mark counters for all
currently running processes. It runs in a separate process because it
needs dac_override capability.
The binary is invoked from a system service by flipping
sys.rss_hwm_reset.on property.
Bug: 119603799
Test: setprop sys.rss_hwm_reset.on 1
Change-Id: Ie853df3f11a3abb5faed9060a103770f11dd4848
diff --git a/cmds/rss_hwm_reset/Android.bp b/cmds/rss_hwm_reset/Android.bp
new file mode 100644
index 0000000..15f10ef
--- /dev/null
+++ b/cmds/rss_hwm_reset/Android.bp
@@ -0,0 +1,28 @@
+// 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"],
+}
diff --git a/cmds/rss_hwm_reset/rss_hwm_reset.cc b/cmds/rss_hwm_reset/rss_hwm_reset.cc
new file mode 100644
index 0000000..1626e7e
--- /dev/null
+++ b/cmds/rss_hwm_reset/rss_hwm_reset.cc
@@ -0,0 +1,72 @@
+/*
+ * 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;
+}
diff --git a/cmds/rss_hwm_reset/rss_hwm_reset.rc b/cmds/rss_hwm_reset/rss_hwm_reset.rc
new file mode 100644
index 0000000..fbbc820
--- /dev/null
+++ b/cmds/rss_hwm_reset/rss_hwm_reset.rc
@@ -0,0 +1,26 @@
+# 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