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src/os/linux/vm/os_linux.cpp
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@@ -1,7 +1,7 @@
/*
- * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
+ * 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.
@@ -102,10 +102,18 @@
# 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
@@ -5014,16 +5022,46 @@
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() {
- // 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;
+ 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;
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