1.1 --- a/src/os/linux/vm/os_linux.cpp Thu Jul 07 15:44:34 2011 -0700
1.2 +++ b/src/os/linux/vm/os_linux.cpp Mon Jul 11 14:15:43 2011 -0700
1.3 @@ -169,7 +169,35 @@
1.4 /* Used to protect dlsym() calls */
1.5 static pthread_mutex_t dl_mutex;
1.6
1.7 -////////////////////////////////////////////////////////////////////////////////
1.8 +#ifdef JAVASE_EMBEDDED
1.9 +class MemNotifyThread: public Thread {
1.10 + friend class VMStructs;
1.11 + public:
1.12 + virtual void run();
1.13 +
1.14 + private:
1.15 + static MemNotifyThread* _memnotify_thread;
1.16 + int _fd;
1.17 +
1.18 + public:
1.19 +
1.20 + // Constructor
1.21 + MemNotifyThread(int fd);
1.22 +
1.23 + // Tester
1.24 + bool is_memnotify_thread() const { return true; }
1.25 +
1.26 + // Printing
1.27 + char* name() const { return (char*)"Linux MemNotify Thread"; }
1.28 +
1.29 + // Returns the single instance of the MemNotifyThread
1.30 + static MemNotifyThread* memnotify_thread() { return _memnotify_thread; }
1.31 +
1.32 + // Create and start the single instance of MemNotifyThread
1.33 + static void start();
1.34 +};
1.35 +#endif // JAVASE_EMBEDDED
1.36 +
1.37 // utility functions
1.38
1.39 static int SR_initialize();
1.40 @@ -4245,7 +4273,16 @@
1.41 }
1.42
1.43 // this is called at the end of vm_initialization
1.44 -void os::init_3(void) { }
1.45 +void os::init_3(void)
1.46 +{
1.47 +#ifdef JAVASE_EMBEDDED
1.48 + // Start the MemNotifyThread
1.49 + if (LowMemoryProtection) {
1.50 + MemNotifyThread::start();
1.51 + }
1.52 + return;
1.53 +#endif
1.54 +}
1.55
1.56 // Mark the polling page as unreadable
1.57 void os::make_polling_page_unreadable(void) {
1.58 @@ -5368,3 +5405,78 @@
1.59 return true;
1.60 }
1.61
1.62 +
1.63 +#ifdef JAVASE_EMBEDDED
1.64 +//
1.65 +// A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory.
1.66 +//
1.67 +MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL;
1.68 +
1.69 +// ctor
1.70 +//
1.71 +MemNotifyThread::MemNotifyThread(int fd): Thread() {
1.72 + assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread");
1.73 + _fd = fd;
1.74 +
1.75 + if (os::create_thread(this, os::os_thread)) {
1.76 + _memnotify_thread = this;
1.77 + os::set_priority(this, NearMaxPriority);
1.78 + os::start_thread(this);
1.79 + }
1.80 +}
1.81 +
1.82 +// Where all the work gets done
1.83 +//
1.84 +void MemNotifyThread::run() {
1.85 + assert(this == memnotify_thread(), "expected the singleton MemNotifyThread");
1.86 +
1.87 + // Set up the select arguments
1.88 + fd_set rfds;
1.89 + if (_fd != -1) {
1.90 + FD_ZERO(&rfds);
1.91 + FD_SET(_fd, &rfds);
1.92 + }
1.93 +
1.94 + // Now wait for the mem_notify device to wake up
1.95 + while (1) {
1.96 + // Wait for the mem_notify device to signal us..
1.97 + int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL);
1.98 + if (rc == -1) {
1.99 + perror("select!\n");
1.100 + break;
1.101 + } else if (rc) {
1.102 + //ssize_t free_before = os::available_memory();
1.103 + //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024);
1.104 +
1.105 + // The kernel is telling us there is not much memory left...
1.106 + // try to do something about that
1.107 +
1.108 + // If we are not already in a GC, try one.
1.109 + if (!Universe::heap()->is_gc_active()) {
1.110 + Universe::heap()->collect(GCCause::_allocation_failure);
1.111 +
1.112 + //ssize_t free_after = os::available_memory();
1.113 + //tty->print ("Post-Notify: Free: %dK\n",free_after/1024);
1.114 + //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024);
1.115 + }
1.116 + // We might want to do something like the following if we find the GC's are not helping...
1.117 + // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true);
1.118 + }
1.119 + }
1.120 +}
1.121 +
1.122 +//
1.123 +// See if the /dev/mem_notify device exists, and if so, start a thread to monitor it.
1.124 +//
1.125 +void MemNotifyThread::start() {
1.126 + int fd;
1.127 + fd = open ("/dev/mem_notify", O_RDONLY, 0);
1.128 + if (fd < 0) {
1.129 + return;
1.130 + }
1.131 +
1.132 + if (memnotify_thread() == NULL) {
1.133 + new MemNotifyThread(fd);
1.134 + }
1.135 +}
1.136 +#endif // JAVASE_EMBEDDED
