libpsi: initial revision
New library to create, register and destroy PSI monitors in a consistent
way with lmkd.
Test: used within lmkd
Bug: 111308141
Change-Id: If243a97f178e90fe41e2de90c7b858ba82440279
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
diff --git a/lmkd/libpsi/psi.c b/lmkd/libpsi/psi.c
new file mode 100644
index 0000000..f4d5d18
--- /dev/null
+++ b/lmkd/libpsi/psi.c
@@ -0,0 +1,99 @@
+/*
+ * 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
+ *
+ * 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.
+ */
+
+#define LOG_TAG "libpsi"
+
+#include <errno.h>
+#include <string.h>
+#include <sys/epoll.h>
+
+#include <log/log.h>
+#include "psi/psi.h"
+
+#define PSI_MON_FILE_MEMORY "/proc/pressure/memory"
+
+static const char* stall_type_name[] = {
+ "some",
+ "full",
+};
+
+int init_psi_monitor(enum psi_stall_type stall_type,
+ int threshold_us, int window_us) {
+ int fd;
+ int res;
+ char buf[256];
+
+ fd = TEMP_FAILURE_RETRY(open(PSI_MON_FILE_MEMORY, O_WRONLY | O_CLOEXEC));
+ if (fd < 0) {
+ ALOGE("No kernel psi monitor support (errno=%d)", errno);
+ return -1;
+ }
+
+ switch (stall_type) {
+ case (PSI_SOME):
+ case (PSI_FULL):
+ res = snprintf(buf, sizeof(buf), "%s %d %d",
+ stall_type_name[stall_type], threshold_us, window_us);
+ break;
+ default:
+ ALOGE("Invalid psi stall type: %d", stall_type);
+ errno = EINVAL;
+ goto err;
+ }
+
+ if (res >= (ssize_t)sizeof(buf)) {
+ ALOGE("%s line overflow for psi stall type '%s'",
+ PSI_MON_FILE_MEMORY, stall_type_name[stall_type]);
+ errno = EINVAL;
+ goto err;
+ }
+
+ res = TEMP_FAILURE_RETRY(write(fd, buf, strlen(buf) + 1));
+ if (res < 0) {
+ ALOGE("%s write failed for psi stall type '%s'; errno=%d",
+ PSI_MON_FILE_MEMORY, stall_type_name[stall_type], errno);
+ goto err;
+ }
+
+ return fd;
+
+err:
+ close(fd);
+ return -1;
+}
+
+int register_psi_monitor(int epollfd, int fd, void* data) {
+ int res;
+ struct epoll_event epev;
+
+ epev.events = EPOLLPRI;
+ epev.data.ptr = data;
+ res = epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &epev);
+ if (res < 0) {
+ ALOGE("epoll_ctl for psi monitor failed; errno=%d", errno);
+ }
+ return res;
+}
+
+int unregister_psi_monitor(int epollfd, int fd) {
+ return epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, NULL);
+}
+
+void destroy_psi_monitor(int fd) {
+ if (fd >= 0) {
+ close(fd);
+ }
+}