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8147910: Cache initial active_processor_count

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Introduce and initialize active_processor_count variable in VM.

Reviewed-by: dholmes, jprovino
This commit is contained in:
Thomas Schatzl 2016-07-26 11:04:20 +02:00
parent da3339948e
commit 7c45404684
2 changed files with 24 additions and 3 deletions
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14
hotspot/src/share/vm/runtime/os.cpp
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@ -71,6 +71,7 @@ volatile int32_t* os::_mem_serialize_page = NULL;
uintptr_t os::_serialize_page_mask = 0; uintptr_t os::_serialize_page_mask = 0;
long os::_rand_seed = 1; long os::_rand_seed = 1;
int os::_processor_count = 0; int os::_processor_count = 0;
int os::_initial_active_processor_count = 0;
size_t os::_page_sizes[os::page_sizes_max]; size_t os::_page_sizes[os::page_sizes_max];
#ifndef PRODUCT #ifndef PRODUCT
@ -315,6 +316,7 @@ static void signal_thread_entry(JavaThread* thread, TRAPS) {
} }
void os::init_before_ergo() { void os::init_before_ergo() {
initialize_initial_active_processor_count();
// We need to initialize large page support here because ergonomics takes some // We need to initialize large page support here because ergonomics takes some
// decisions depending on large page support and the calculated large page size. // decisions depending on large page support and the calculated large page size.
large_page_init(); large_page_init();
@ -829,7 +831,11 @@ void os::print_cpu_info(outputStream* st, char* buf, size_t buflen) {
st->print("CPU:"); st->print("CPU:");
st->print("total %d", os::processor_count()); st->print("total %d", os::processor_count());
// It's not safe to query number of active processors after crash // It's not safe to query number of active processors after crash
// st->print("(active %d)", os::active_processor_count()); // st->print("(active %d)", os::active_processor_count()); but we can
// print the initial number of active processors.
// We access the raw value here because the assert in the accessor will
// fail if the crash occurs before initialization of this value.
st->print(" (initial active %d)", _initial_active_processor_count);
st->print(" %s", VM_Version::features_string()); st->print(" %s", VM_Version::features_string());
st->cr(); st->cr();
pd_print_cpu_info(st, buf, buflen); pd_print_cpu_info(st, buf, buflen);
@ -1597,6 +1603,12 @@ bool os::is_server_class_machine() {
return result; return result;
} }
void os::initialize_initial_active_processor_count() {
assert(_initial_active_processor_count == 0, "Initial active processor count already set.");
_initial_active_processor_count = active_processor_count();
log_debug(os)("Initial active processor count set to %d" , _initial_active_processor_count);
}
void os::SuspendedThreadTask::run() { void os::SuspendedThreadTask::run() {
assert(Threads_lock->owned_by_self() || (_thread == VMThread::vm_thread()), "must have threads lock to call this"); assert(Threads_lock->owned_by_self() || (_thread == VMThread::vm_thread()), "must have threads lock to call this");
internal_do_task(); internal_do_task();

13
hotspot/src/share/vm/runtime/os.hpp
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@ -140,6 +140,7 @@ class os: AllStatic {
static void get_summary_cpu_info(char* buf, size_t buflen); static void get_summary_cpu_info(char* buf, size_t buflen);
static void get_summary_os_info(char* buf, size_t buflen); static void get_summary_os_info(char* buf, size_t buflen);
static void initialize_initial_active_processor_count();
public: public:
static void init(void); // Called before command line parsing static void init(void); // Called before command line parsing
static void init_before_ergo(void); // Called after command line parsing static void init_before_ergo(void); // Called after command line parsing
@ -227,6 +228,13 @@ class os: AllStatic {
// Note that on some OSes this can change dynamically. // Note that on some OSes this can change dynamically.
static int active_processor_count(); static int active_processor_count();
// At startup the number of active CPUs this process is allowed to run on.
// This value does not change dynamically. May be different from active_processor_count().
static int initial_active_processor_count() {
assert(_initial_active_processor_count > 0, "Initial active processor count not set yet.");
return _initial_active_processor_count;
}
// Bind processes to processors. // Bind processes to processors.
// This is a two step procedure: // This is a two step procedure:
// first you generate a distribution of processes to processors, // first you generate a distribution of processes to processors,
@ -948,8 +956,9 @@ class os: AllStatic {
protected: protected:
static long _rand_seed; // seed for random number generator static long _rand_seed; // seed for random number generator
static int _processor_count; // number of processors static int _processor_count; // number of processors
static int _initial_active_processor_count; // number of active processors during initialization.
static char* format_boot_path(const char* format_string, static char* format_boot_path(const char* format_string,
const char* home, const char* home,