graal-jvmci-8: src/os/linux/vm/os

comparison src/os/linux/vm/os_linux.cpp @ 3802:b0b8491925fe

7061212: use o/s low memory notification in embedded builds Reviewed-by: dholmes, never, jwilhelm, kvn

author	jcoomes
date	Mon, 11 Jul 2011 14:15:43 -0700
parents	bf6481e5f96d
children	a20e6e447d3d

comparison

equal deleted inserted replaced

-:8a4fc2990229
+:b0b8491925fe
 sigset_t SR_sigset;
 /* Used to protect dlsym() calls */
 static pthread_mutex_t dl_mutex;
-////////////////////////////////////////////////////////////////////////////////
+#ifdef JAVASE_EMBEDDED
+class MemNotifyThread: public Thread {
+friend class VMStructs;
+public:
+virtual void run();
+private:
+static MemNotifyThread* _memnotify_thread;
+int _fd;
+public:
+// Constructor
+MemNotifyThread(int fd);
+// Tester
+bool is_memnotify_thread() const { return true; }
+// Printing
+char* name() const { return (char*)"Linux MemNotify Thread"; }
+// Returns the single instance of the MemNotifyThread
+static MemNotifyThread* memnotify_thread() { return _memnotify_thread; }
+// Create and start the single instance of MemNotifyThread
+static void start();
+};
+#endif // JAVASE_EMBEDDED
 // utility functions
 static int SR_initialize();
 static int SR_finalize();
 return JNI_OK;
 }
 // this is called at the end of vm_initialization
-void os::init_3(void) { }
+void os::init_3(void)
+{
+#ifdef JAVASE_EMBEDDED
+// Start the MemNotifyThread
+if (LowMemoryProtection) {
+MemNotifyThread::start();
+}
+return;
+#endif
+}
 // Mark the polling page as unreadable
 void os::make_polling_page_unreadable(void) {
 if( !guard_memory((char*)_polling_page, Linux::page_size()) )
 fatal("Could not disable polling page");
 if (::stat(libmawtpath, &statbuf) == 0) return false;
 return true;
 }
+#ifdef JAVASE_EMBEDDED
+//
+// A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory.
+//
+MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL;
+// ctor
+//
+MemNotifyThread::MemNotifyThread(int fd): Thread() {
+assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread");
+_fd = fd;
+if (os::create_thread(this, os::os_thread)) {
+_memnotify_thread = this;
+os::set_priority(this, NearMaxPriority);
+os::start_thread(this);
+}
+}
+// Where all the work gets done
+//
+void MemNotifyThread::run() {
+assert(this == memnotify_thread(), "expected the singleton MemNotifyThread");
+// Set up the select arguments
+fd_set rfds;
+if (_fd != -1) {
+FD_ZERO(&rfds);
+FD_SET(_fd, &rfds);
+}
+// Now wait for the mem_notify device to wake up
+while (1) {
+// Wait for the mem_notify device to signal us..
+int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL);
+if (rc == -1) {
+perror("select!\n");
+break;
+} else if (rc) {
+//ssize_t free_before = os::available_memory();
+//tty->print ("Notified: Free: %dK \n",os::available_memory()/1024);
+// The kernel is telling us there is not much memory left...
+// try to do something about that
+// If we are not already in a GC, try one.
+if (!Universe::heap()->is_gc_active()) {
+Universe::heap()->collect(GCCause::_allocation_failure);
+//ssize_t free_after = os::available_memory();
+//tty->print ("Post-Notify: Free: %dK\n",free_after/1024);
+//tty->print ("GC freed: %dK\n", (free_after - free_before)/1024);
+}
+// We might want to do something like the following if we find the GC's are not helping...
+// Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true);
+}
+}
+}
+//
+// See if the /dev/mem_notify device exists, and if so, start a thread to monitor it.
+//
+void MemNotifyThread::start() {
+int    fd;
+fd = open ("/dev/mem_notify", O_RDONLY, 0);
+if (fd < 0) {
+return;
+}
+if (memnotify_thread() == NULL) {
+new MemNotifyThread(fd);
+}
+}
+#endif // JAVASE_EMBEDDED

Mercurial > hg > graal-jvmci-8

comparison src/os/linux/vm/os_linux.cpp @ 3802:b0b8491925fe