--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os_cpu/linux_aarch64/gc/z/zPhysicalMemoryBacking_linux_aarch64.cpp Thu Jun 13 15:24:34 2019 +0100
@@ -0,0 +1,333 @@
+/*
+ * Copyright (c) 2015, 2019, 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.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zAddress.inline.hpp"
+#include "gc/z/zBackingFile_linux_aarch64.hpp"
+#include "gc/z/zErrno.hpp"
+#include "gc/z/zGlobals.hpp"
+#include "gc/z/zLargePages.inline.hpp"
+#include "gc/z/zMemory.hpp"
+#include "gc/z/zNUMA.hpp"
+#include "gc/z/zPhysicalMemory.inline.hpp"
+#include "gc/z/zPhysicalMemoryBacking_linux_aarch64.hpp"
+#include "logging/log.hpp"
+#include "runtime/init.hpp"
+#include "runtime/os.hpp"
+#include "utilities/align.hpp"
+#include "utilities/debug.hpp"
+
+#include <stdio.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+
+//
+// Support for building on older Linux systems
+//
+
+// madvise(2) flags
+#ifndef MADV_HUGEPAGE
+#define MADV_HUGEPAGE 14
+#endif
+
+// Proc file entry for max map mount
+#define ZFILENAME_PROC_MAX_MAP_COUNT "/proc/sys/vm/max_map_count"
+
+bool ZPhysicalMemoryBacking::is_initialized() const {
+ return _file.is_initialized();
+}
+
+void ZPhysicalMemoryBacking::warn_available_space(size_t max) const {
+ // Note that the available space on a tmpfs or a hugetlbfs filesystem
+ // will be zero if no size limit was specified when it was mounted.
+ const size_t available = _file.available();
+ if (available == 0) {
+ // No size limit set, skip check
+ log_info(gc, init)("Available space on backing filesystem: N/A");
+ return;
+ }
+
+ log_info(gc, init)("Available space on backing filesystem: " SIZE_FORMAT "M", available / M);
+
+ // Warn if the filesystem doesn't currently have enough space available to hold
+ // the max heap size. The max heap size will be capped if we later hit this limit
+ // when trying to expand the heap.
+ if (available < max) {
+ log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****");
+ log_warning(gc)("Not enough space available on the backing filesystem to hold the current max Java heap");
+ log_warning(gc)("size (" SIZE_FORMAT "M). Please adjust the size of the backing filesystem accordingly "
+ "(available", max / M);
+ log_warning(gc)("space is currently " SIZE_FORMAT "M). Continuing execution with the current filesystem "
+ "size could", available / M);
+ log_warning(gc)("lead to a premature OutOfMemoryError being thrown, due to failure to map memory.");
+ }
+}
+
+void ZPhysicalMemoryBacking::warn_max_map_count(size_t max) const {
+ const char* const filename = ZFILENAME_PROC_MAX_MAP_COUNT;
+ FILE* const file = fopen(filename, "r");
+ if (file == NULL) {
+ // Failed to open file, skip check
+ log_debug(gc, init)("Failed to open %s", filename);
+ return;
+ }
+
+ size_t actual_max_map_count = 0;
+ const int result = fscanf(file, SIZE_FORMAT, &actual_max_map_count);
+ fclose(file);
+ if (result != 1) {
+ // Failed to read file, skip check
+ log_debug(gc, init)("Failed to read %s", filename);
+ return;
+ }
+
+ // The required max map count is impossible to calculate exactly since subsystems
+ // other than ZGC are also creating memory mappings, and we have no control over that.
+ // However, ZGC tends to create the most mappings and dominate the total count.
+ // In the worst cases, ZGC will map each granule three times, i.e. once per heap view.
+ // We speculate that we need another 20% to allow for non-ZGC subsystems to map memory.
+ const size_t required_max_map_count = (max / ZGranuleSize) * 3 * 1.2;
+ if (actual_max_map_count < required_max_map_count) {
+ log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****");
+ log_warning(gc)("The system limit on number of memory mappings per process might be too low for the given");
+ log_warning(gc)("max Java heap size (" SIZE_FORMAT "M). Please adjust %s to allow for at",
+ max / M, filename);
+ log_warning(gc)("least " SIZE_FORMAT " mappings (current limit is " SIZE_FORMAT "). Continuing execution "
+ "with the current", required_max_map_count, actual_max_map_count);
+ log_warning(gc)("limit could lead to a fatal error, due to failure to map memory.");
+ }
+}
+
+void ZPhysicalMemoryBacking::warn_commit_limits(size_t max) const {
+ // Warn if available space is too low
+ warn_available_space(max);
+
+ // Warn if max map count is too low
+ warn_max_map_count(max);
+}
+
+bool ZPhysicalMemoryBacking::supports_uncommit() {
+ assert(!is_init_completed(), "Invalid state");
+ assert(_file.size() >= ZGranuleSize, "Invalid size");
+
+ // Test if uncommit is supported by uncommitting and then re-committing a granule
+ return commit(uncommit(ZGranuleSize)) == ZGranuleSize;
+}
+
+size_t ZPhysicalMemoryBacking::commit(size_t size) {
+ size_t committed = 0;
+
+ // Fill holes in the backing file
+ while (committed < size) {
+ size_t allocated = 0;
+ const size_t remaining = size - committed;
+ const uintptr_t start = _uncommitted.alloc_from_front_at_most(remaining, &allocated);
+ if (start == UINTPTR_MAX) {
+ // No holes to commit
+ break;
+ }
+
+ // Try commit hole
+ const size_t filled = _file.commit(start, allocated);
+ if (filled > 0) {
+ // Successful or partialy successful
+ _committed.free(start, filled);
+ committed += filled;
+ }
+ if (filled < allocated) {
+ // Failed or partialy failed
+ _uncommitted.free(start + filled, allocated - filled);
+ return committed;
+ }
+ }
+
+ // Expand backing file
+ if (committed < size) {
+ const size_t remaining = size - committed;
+ const uintptr_t start = _file.size();
+ const size_t expanded = _file.commit(start, remaining);
+ if (expanded > 0) {
+ // Successful or partialy successful
+ _committed.free(start, expanded);
+ committed += expanded;
+ }
+ }
+
+ return committed;
+}
+
+size_t ZPhysicalMemoryBacking::uncommit(size_t size) {
+ size_t uncommitted = 0;
+
+ // Punch holes in backing file
+ while (uncommitted < size) {
+ size_t allocated = 0;
+ const size_t remaining = size - uncommitted;
+ const uintptr_t start = _committed.alloc_from_back_at_most(remaining, &allocated);
+ assert(start != UINTPTR_MAX, "Allocation should never fail");
+
+ // Try punch hole
+ const size_t punched = _file.uncommit(start, allocated);
+ if (punched > 0) {
+ // Successful or partialy successful
+ _uncommitted.free(start, punched);
+ uncommitted += punched;
+ }
+ if (punched < allocated) {
+ // Failed or partialy failed
+ _committed.free(start + punched, allocated - punched);
+ return uncommitted;
+ }
+ }
+
+ return uncommitted;
+}
+
+ZPhysicalMemory ZPhysicalMemoryBacking::alloc(size_t size) {
+ assert(is_aligned(size, ZGranuleSize), "Invalid size");
+
+ ZPhysicalMemory pmem;
+
+ // Allocate segments
+ for (size_t allocated = 0; allocated < size; allocated += ZGranuleSize) {
+ const uintptr_t start = _committed.alloc_from_front(ZGranuleSize);
+ assert(start != UINTPTR_MAX, "Allocation should never fail");
+ pmem.add_segment(ZPhysicalMemorySegment(start, ZGranuleSize));
+ }
+
+ return pmem;
+}
+
+void ZPhysicalMemoryBacking::free(const ZPhysicalMemory& pmem) {
+ const size_t nsegments = pmem.nsegments();
+
+ // Free segments
+ for (size_t i = 0; i < nsegments; i++) {
+ const ZPhysicalMemorySegment& segment = pmem.segment(i);
+ _committed.free(segment.start(), segment.size());
+ }
+}
+
+void ZPhysicalMemoryBacking::map_failed(ZErrno err) const {
+ if (err == ENOMEM) {
+ fatal("Failed to map memory. Please check the system limit on number of "
+ "memory mappings allowed per process (see %s)", ZFILENAME_PROC_MAX_MAP_COUNT);
+ } else {
+ fatal("Failed to map memory (%s)", err.to_string());
+ }
+}
+
+void ZPhysicalMemoryBacking::advise_view(uintptr_t addr, size_t size, int advice) const {
+ if (madvise((void*)addr, size, advice) == -1) {
+ ZErrno err;
+ log_error(gc)("Failed to advise on memory (advice %d, %s)", advice, err.to_string());
+ }
+}
+
+void ZPhysicalMemoryBacking::pretouch_view(uintptr_t addr, size_t size) const {
+ const size_t page_size = ZLargePages::is_explicit() ? os::large_page_size() : os::vm_page_size();
+ os::pretouch_memory((void*)addr, (void*)(addr + size), page_size);
+}
+
+void ZPhysicalMemoryBacking::map_view(const ZPhysicalMemory& pmem, uintptr_t addr, bool pretouch) const {
+ const size_t nsegments = pmem.nsegments();
+ size_t size = 0;
+
+ // Map segments
+ for (size_t i = 0; i < nsegments; i++) {
+ const ZPhysicalMemorySegment& segment = pmem.segment(i);
+ const uintptr_t segment_addr = addr + size;
+ const void* const res = mmap((void*)segment_addr, segment.size(), PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, _file.fd(), segment.start());
+ if (res == MAP_FAILED) {
+ ZErrno err;
+ map_failed(err);
+ }
+
+ size += segment.size();
+ }
+
+ // Advise on use of transparent huge pages before touching it
+ if (ZLargePages::is_transparent()) {
+ advise_view(addr, size, MADV_HUGEPAGE);
+ }
+
+ // NUMA interleave memory before touching it
+ ZNUMA::memory_interleave(addr, size);
+
+ // Pre-touch memory
+ if (pretouch) {
+ pretouch_view(addr, size);
+ }
+}
+
+void ZPhysicalMemoryBacking::unmap_view(const ZPhysicalMemory& pmem, uintptr_t addr) const {
+ // Note that we must keep the address space reservation intact and just detach
+ // the backing memory. For this reason we map a new anonymous, non-accessible
+ // and non-reserved page over the mapping instead of actually unmapping.
+ const void* const res = mmap((void*)addr, pmem.size(), PROT_NONE, MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, -1, 0);
+ if (res == MAP_FAILED) {
+ ZErrno err;
+ map_failed(err);
+ }
+}
+
+uintptr_t ZPhysicalMemoryBacking::nmt_address(uintptr_t offset) const {
+ // From an NMT point of view we treat the first heap view (marked0) as committed
+ return ZAddress::marked0(offset);
+}
+
+void ZPhysicalMemoryBacking::map(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+ if (ZVerifyViews) {
+ // Map good view
+ map_view(pmem, ZAddress::good(offset), AlwaysPreTouch);
+ } else {
+ // Map all views
+ map_view(pmem, ZAddress::marked0(offset), AlwaysPreTouch);
+ map_view(pmem, ZAddress::marked1(offset), AlwaysPreTouch);
+ map_view(pmem, ZAddress::remapped(offset), AlwaysPreTouch);
+ }
+}
+
+void ZPhysicalMemoryBacking::unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+ if (ZVerifyViews) {
+ // Unmap good view
+ unmap_view(pmem, ZAddress::good(offset));
+ } else {
+ // Unmap all views
+ unmap_view(pmem, ZAddress::marked0(offset));
+ unmap_view(pmem, ZAddress::marked1(offset));
+ unmap_view(pmem, ZAddress::remapped(offset));
+ }
+}
+
+void ZPhysicalMemoryBacking::debug_map(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+ // Map good view
+ assert(ZVerifyViews, "Should be enabled");
+ map_view(pmem, ZAddress::good(offset), false /* pretouch */);
+}
+
+void ZPhysicalMemoryBacking::debug_unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+ // Unmap good view
+ assert(ZVerifyViews, "Should be enabled");
+ unmap_view(pmem, ZAddress::good(offset));
+}