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8254972: Fix pretouch chunk calculations

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Reviewed-by: sjohanss, kbarrett
This commit is contained in:
Thomas Schatzl 2020-10-30 08:45:34 +00:00
parent d12819158a
commit 2c7fc85be9
2 changed files with 31 additions and 16 deletions
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44
src/hotspot/share/gc/shared/pretouchTask.cpp
View File

@ -28,17 +28,21 @@
#include "runtime/globals.hpp"
#include "runtime/os.hpp"
PretouchTask::PretouchTask(const char* task_name, char* start_address, char* end_address, size_t page_size) :
PretouchTask::PretouchTask(const char* task_name,
char* start_address,
char* end_address,
size_t page_size,
size_t chunk_size) :
AbstractGangTask(task_name),
_cur_addr(start_address),
_start_addr(start_address),
_end_addr(end_address),
_page_size(0) {
#ifdef LINUX
_page_size = UseTransparentHugePages ? (size_t)os::vm_page_size(): page_size;
#else
_page_size = page_size;
#endif
_page_size(page_size),
_chunk_size(chunk_size) {
assert(chunk_size >= page_size,
"Chunk size " SIZE_FORMAT " is smaller than page size " SIZE_FORMAT,
chunk_size, page_size);
}
size_t PretouchTask::chunk_size() {
@ -46,15 +50,13 @@ size_t PretouchTask::chunk_size() {
}
void PretouchTask::work(uint worker_id) {
size_t const actual_chunk_size = MAX2(chunk_size(), _page_size);
while (true) {
char* touch_addr = Atomic::fetch_and_add(&_cur_addr, actual_chunk_size);
char* touch_addr = Atomic::fetch_and_add(&_cur_addr, _chunk_size);
if (touch_addr < _start_addr || touch_addr >= _end_addr) {
break;
}
char* end_addr = touch_addr + MIN2(actual_chunk_size, pointer_delta(_end_addr, touch_addr, sizeof(char)));
char* end_addr = touch_addr + MIN2(_chunk_size, pointer_delta(_end_addr, touch_addr, sizeof(char)));
os::pretouch_memory(touch_addr, end_addr, _page_size);
}
@ -62,13 +64,25 @@ void PretouchTask::work(uint worker_id) {
void PretouchTask::pretouch(const char* task_name, char* start_address, char* end_address,
size_t page_size, WorkGang* pretouch_gang) {
PretouchTask task(task_name, start_address, end_address, page_size);
#ifdef LINUX
// When using THP we need to always pre-touch using small pages as the OS will
// initially always use small pages.
page_size = UseTransparentHugePages ? (size_t)os::vm_page_size() : page_size;
#endif
size_t chunk_size = MAX2(PretouchTask::chunk_size(), page_size);
PretouchTask task(task_name, start_address, end_address, page_size, chunk_size);
size_t total_bytes = pointer_delta(end_address, start_address, sizeof(char));
if (pretouch_gang != NULL) {
size_t num_chunks = MAX2((size_t)1, total_bytes / MAX2(PretouchTask::chunk_size(), page_size));
if (total_bytes == 0) {
return;
}
uint num_workers = MIN2((uint)num_chunks, pretouch_gang->total_workers());
if (pretouch_gang != NULL) {
size_t num_chunks = (total_bytes + chunk_size - 1) / chunk_size;
uint num_workers = (uint)MIN2(num_chunks, (size_t)pretouch_gang->total_workers());
log_debug(gc, heap)("Running %s with %u workers for " SIZE_FORMAT " work units pre-touching " SIZE_FORMAT "B.",
task.name(), num_workers, num_chunks, total_bytes);

3
src/hotspot/share/gc/shared/pretouchTask.hpp
View File

@ -32,9 +32,10 @@ class PretouchTask : public AbstractGangTask {
char* const _start_addr;
char* const _end_addr;
size_t _page_size;
size_t _chunk_size;
public:
PretouchTask(const char* task_name, char* start_address, char* end_address, size_t page_size);
PretouchTask(const char* task_name, char* start_address, char* end_address, size_t page_size, size_t chunk_size);
virtual void work(uint worker_id);