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8227006: [linux] Runtime.availableProcessors execution time increased by factor of 100

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Reviewed-by: dholmes, sgehwolf, redestad
This commit is contained in:
Bob Vandette 2019-10-31 19:32:41 +00:00
parent 7df849224b
commit f5632e62b2
2 changed files with 34 additions and 8 deletions
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37
src/hotspot/os/linux/osContainer_linux.cpp
View File

@ -54,12 +54,16 @@
bool OSContainer::_is_initialized = false;
bool OSContainer::_is_containerized = false;
int OSContainer::_active_processor_count = 1;
julong _unlimited_memory;
class CgroupSubsystem: CHeapObj<mtInternal> {
friend class OSContainer;
private:
volatile jlong _next_check_counter;
/* mountinfo contents */
char *_root;
char *_mount_point;
@ -72,6 +76,7 @@ class CgroupSubsystem: CHeapObj<mtInternal> {
_root = os::strdup(root);
_mount_point = os::strdup(mountpoint);
_path = NULL;
_next_check_counter = min_jlong;
}
/*
@ -121,6 +126,14 @@ class CgroupSubsystem: CHeapObj<mtInternal> {
}
char *subsystem_path() { return _path; }
bool cache_has_expired() {
return os::elapsed_counter() > _next_check_counter;
}
void set_cache_expiry_time(jlong timeout) {
_next_check_counter = os::elapsed_counter() + timeout;
}
};
class CgroupMemorySubsystem: CgroupSubsystem {
@ -132,31 +145,26 @@ class CgroupMemorySubsystem: CgroupSubsystem {
* file if everything else seems unlimited */
bool _uses_mem_hierarchy;
volatile jlong _memory_limit_in_bytes;
volatile jlong _next_check_counter;
public:
CgroupMemorySubsystem(char *root, char *mountpoint) : CgroupSubsystem::CgroupSubsystem(root, mountpoint) {
_uses_mem_hierarchy = false;
_memory_limit_in_bytes = -1;
_next_check_counter = min_jlong;
}
bool is_hierarchical() { return _uses_mem_hierarchy; }
void set_hierarchical(bool value) { _uses_mem_hierarchy = value; }
bool should_check_memory_limit() {
return os::elapsed_counter() > _next_check_counter;
}
jlong memory_limit_in_bytes() { return _memory_limit_in_bytes; }
void set_memory_limit_in_bytes(jlong value) {
_memory_limit_in_bytes = value;
// max memory limit is unlikely to change, but we want to remain
// responsive to configuration changes. A very short (20ms) grace time
// responsive to configuration changes. A very short grace time
// between re-read avoids excessive overhead during startup without
// significantly reducing the VMs ability to promptly react to reduced
// memory availability
_next_check_counter = os::elapsed_counter() + (NANOSECS_PER_SEC/50);
set_cache_expiry_time(OSCONTAINER_CACHE_TIMEOUT);
}
};
@ -481,7 +489,7 @@ jlong OSContainer::uses_mem_hierarchy() {
* OSCONTAINER_ERROR for not supported
*/
jlong OSContainer::memory_limit_in_bytes() {
if (!memory->should_check_memory_limit()) {
if (!memory->cache_has_expired()) {
return memory->memory_limit_in_bytes();
}
jlong memory_limit = read_memory_limit_in_bytes();
@ -617,6 +625,14 @@ int OSContainer::active_processor_count() {
int cpu_count, limit_count;
int result;
// We use a cache with a timeout to avoid performing expensive
// computations in the event this function is called frequently.
// [See 8227006].
if (!cpu->cache_has_expired()) {
log_trace(os, container)("OSContainer::active_processor_count (cached): %d", OSContainer::_active_processor_count);
return OSContainer::_active_processor_count;
}
cpu_count = limit_count = os::Linux::active_processor_count();
int quota = cpu_quota();
int period = cpu_period();
@ -649,6 +665,11 @@ int OSContainer::active_processor_count() {
result = MIN2(cpu_count, limit_count);
log_trace(os, container)("OSContainer::active_processor_count: %d", result);
// Update the value and reset the cache timeout
OSContainer::_active_processor_count = result;
cpu->set_cache_expiry_time(OSCONTAINER_CACHE_TIMEOUT);
return result;
}

5
src/hotspot/os/linux/osContainer_linux.hpp
View File

@ -31,11 +31,16 @@
#define OSCONTAINER_ERROR (-2)
// 20ms timeout between re-reads of memory limit and _active_processor_count.
#define OSCONTAINER_CACHE_TIMEOUT (NANOSECS_PER_SEC/50)
class OSContainer: AllStatic {
private:
static bool _is_initialized;
static bool _is_containerized;
static int _active_processor_count;
static jlong read_memory_limit_in_bytes();
public: