src/os/linux/vm/os_linux.cpp

*** 1,7 ****
  /*
!  * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
--- 1,7 ----
  /*
!  * Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
*** 102,111 ****
--- 102,119 ----
  # include <inttypes.h>
  # include <sys/ioctl.h>
  
  PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
  
+ #ifndef _GNU_SOURCE
+   #define _GNU_SOURCE
+   #include <sched.h>
+   #undef _GNU_SOURCE
+ #else
+   #include <sched.h>
+ #endif
+ 
  // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
  // getrusage() is prepared to handle the associated failure.
  #ifndef RUSAGE_THREAD
  #define RUSAGE_THREAD   (1)               /* only the calling thread */
  #endif
*** 5014,5029 ****
    if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
      fatal("Could not enable polling page");
    }
  };
  
  int os::active_processor_count() {
!   // Linux doesn't yet have a (official) notion of processor sets,
!   // so just return the number of online processors.
!   int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
!   assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
!   return online_cpus;
  }
  
  void os::set_native_thread_name(const char *name) {
    // Not yet implemented.
    return;
--- 5022,5067 ----
    if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
      fatal("Could not enable polling page");
    }
  };
  
+ static int os_cpu_count(const cpu_set_t* cpus) {
+   int count = 0;
+   // only look up to the number of configured processors
+   for (int i = 0; i < os::processor_count(); i++) {
+     if (CPU_ISSET(i, cpus)) {
+       count++;
+     }
+   }
+   return count;
+ }
+ 
+ // Get the current number of available processors for this process.
+ // This value can change at any time during a process's lifetime.
+ // sched_getaffinity gives an accurate answer as it accounts for cpusets.
+ // If anything goes wrong we fallback to returning the number of online
+ // processors - which can be greater than the number available to the process.
  int os::active_processor_count() {
!   cpu_set_t cpus;  // can represent at most 1024 (CPU_SETSIZE) processors
!   int cpus_size = sizeof(cpu_set_t);
!   int cpu_count = 0;
! 
!   // pid 0 means the current thread - which we have to assume represents the process
!   if (sched_getaffinity(0, cpus_size, &cpus) == 0) {
!     cpu_count = os_cpu_count(&cpus);
!     if(PrintActiveCpus) {
!       tty->print_cr("active_processor_count: sched_getaffinity processor count: %d", cpu_count);
!     }
!   }
!   else {
!     cpu_count = ::sysconf(_SC_NPROCESSORS_ONLN);
!     warning("sched_getaffinity failed (%s)- using online processor count (%d) "
!             "which may exceed available processors", strerror(errno), cpu_count);
!   }
! 
!   assert(cpu_count > 0 && cpu_count <= processor_count(), "sanity check");
!   return cpu_count;
  }
  
  void os::set_native_thread_name(const char *name) {
    // Not yet implemented.
    return;