-/* Copyright (c) 2015-2018. The SimGrid Team.
- * All rights reserved. */
+/* Copyright (c) 2015-2021. The SimGrid Team. All rights reserved. */
/* This program is free software; you can redistribute it and/or modify it
* under the terms of the license (GNU LGPL) which comes with this package. */
-#include <cstring> // memcpy, memcmp
-#include <unistd.h>
-
#include <sys/mman.h>
#ifdef __FreeBSD__
#define MAP_POPULATE MAP_PREFAULT_READ
#endif
-#include "xbt/base.h"
+#include "src/internal_config.h"
#include "xbt/log.h"
#include "xbt/sysdep.h"
-#include "src/internal_config.h"
-
-#include "src/mc/sosp/PageStore.hpp"
-
+#include "src/include/xxhash.hpp"
#include "src/mc/mc_mmu.hpp"
+#include "src/mc/sosp/PageStore.hpp"
-XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_page_snapshot, mc, "Logging specific to mc_page_snapshot");
+#include <cstring> // memcpy, memcmp
+#include <unistd.h>
namespace simgrid {
namespace mc {
/** @brief Compute a hash for the given memory page
*
- * The page is used before inserting the page in the page store
- * in order to find duplicate of this page in the page store.
+ * The page is used before inserting the page in the page store in order to find duplicate of this page in the page
+ * store.
*
* @param data Memory page
* @return hash off the page
*/
static XBT_ALWAYS_INLINE PageStore::hash_type mc_hash_page(const void* data)
{
- const std::uint64_t* values = (const uint64_t*)data;
- std::size_t n = xbt_pagesize / sizeof(uint64_t);
-
- // This djb2:
- std::uint64_t hash = 5381;
- for (std::size_t i = 0; i != n; ++i)
- hash = ((hash << 5) + hash) + values[i];
- return hash;
+ return xxh::xxhash<64>(data, xbt_pagesize);
}
// ***** snapshot_page_manager
-PageStore::PageStore(size_t size) : memory_(nullptr), capacity_(size), top_index_(0)
+PageStore::PageStore(std::size_t size) : capacity_(size)
{
// Using mmap in order to be able to expand the region by relocating it somewhere else in the virtual memory space:
void* memory =
// Check if expanding worked
if (new_memory != (char*)this->memory_ + old_bytesize) {
// New memory segment could not be put at the end of this->memory_,
- // so cancel this one and try to rellocate everything and copy data
+ // so cancel this one and try to relocate everything and copy data
munmap(new_memory, new_bytesize - old_bytesize);
new_memory =
mmap(nullptr, new_bytesize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, -1, 0);
std::size_t PageStore::alloc_page()
{
if (this->free_pages_.empty()) {
-
// Expand the region:
if (this->top_index_ == this->capacity_)
// All the pages are allocated, we need add more pages:
// Use a page from the top:
return this->top_index_++;
-
} else {
-
// Use a page from free_pages_ (inside of the region):
size_t res = this->free_pages_[this->free_pages_.size() - 1];
this->free_pages_.pop_back();
}
/** Store a page in memory */
-std::size_t PageStore::store_page(void* page)
+std::size_t PageStore::store_page(const void* page)
{
xbt_assert(top_index_ <= this->capacity_, "top_index is not consistent");
for (size_t const& pageno : page_set) {
const void* snapshot_page = this->get_page(pageno);
if (memcmp(page, snapshot_page, xbt_pagesize) == 0) {
-
// If a page with the same content is already in the page store it's reused and its refcount is incremented.
page_counts_[pageno]++;
return pageno;
// Otherwise, a new page is allocated in the page store and the content of the page is `memcpy()`-ed to this new page.
std::size_t pageno = alloc_page();
xbt_assert(this->page_counts_[pageno] == 0, "Allocated page is already used");
- void* snapshot_page = (void*)this->get_page(pageno);
+ void* snapshot_page = this->get_page(pageno);
memcpy(snapshot_page, page, xbt_pagesize);
page_set.insert(pageno);
page_counts_[pageno]++;
} // namespace mc
} // namespace simgrid
-
-#ifdef SIMGRID_TEST
-
-#include <cstdint>
-#include <cstring>
-
-#include <sys/mman.h>
-#include <unistd.h>
-
-#include <memory>
-
-#include "src/mc/PageStore.hpp"
-
-static int value = 0;
-
-static void new_content(void* data, std::size_t size)
-{
- ::memset(data, ++value, size);
-}
-
-static void* getpage()
-{
- return mmap(nullptr, getpagesize(), PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-}
-
-XBT_TEST_SUITE("mc_page_store", "Page store");
-
-XBT_TEST_UNIT("base", test_mc_page_store, "Test adding/removing pages in the store")
-{
- using simgrid::mc::PageStore;
-
- xbt_test_add("Init");
- std::size_t pagesize = (size_t)getpagesize();
- std::unique_ptr<PageStore> store = std::unique_ptr<PageStore>(new simgrid::mc::PageStore(500));
- void* data = getpage();
- xbt_test_assert(store->size() == 0, "Bad size");
-
- xbt_test_add("Store the page once");
- new_content(data, pagesize);
- size_t pageno1 = store->store_page(data);
- xbt_test_assert(store->get_ref(pageno1) == 1, "Bad refcount");
- const void* copy = store->get_page(pageno1);
- xbt_test_assert(::memcmp(data, copy, pagesize) == 0, "Page data should be the same");
- xbt_test_assert(store->size() == 1, "Bad size");
-
- xbt_test_add("Store the same page again");
- size_t pageno2 = store->store_page(data);
- xbt_test_assert(pageno1 == pageno2, "Page should be the same");
- xbt_test_assert(store->get_ref(pageno1) == 2, "Bad refcount");
- xbt_test_assert(store->size() == 1, "Bad size");
-
- xbt_test_add("Store a new page");
- new_content(data, pagesize);
- size_t pageno3 = store->store_page(data);
- xbt_test_assert(pageno1 != pageno3, "New page should be different");
- xbt_test_assert(store->size() == 2, "Bad size");
-
- xbt_test_add("Unref pages");
- store->unref_page(pageno1);
- xbt_assert(store->get_ref(pageno1) == 1, "Bad refcount");
- xbt_assert(store->size() == 2, "Bad size");
- store->unref_page(pageno2);
- xbt_test_assert(store->size() == 1, "Bad size");
-
- xbt_test_add("Reallocate page");
- new_content(data, pagesize);
- size_t pageno4 = store->store_page(data);
- xbt_test_assert(pageno1 == pageno4, "Page was not reused");
- xbt_test_assert(store->get_ref(pageno4) == 1, "Bad refcount");
- xbt_test_assert(store->size() == 2, "Bad size");
-}
-
-#endif /* SIMGRID_TEST */
