#include "mc_page_store.h"
+#ifdef MC_PAGE_STORE_MD4
+#include <nettle/md4.h>
+#endif
+
#include "mc_mmu.h"
XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_page_snapshot, mc,
/** @brief Compte 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 pae 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 inline __attribute__ ((always_inline))
-uint64_t mc_hash_page(const void* data)
+s_mc_pages_store::hash_type mc_hash_page(const void* data)
{
+#ifdef MC_PAGE_STORE_MD4
+ boost::array<uint64_t,2> result;
+ md4_ctx context;
+ md4_init(&context);
+ md4_update(&context, xbt_pagesize, (const uint8_t*) data);
+ md4_digest(&context, MD4_DIGEST_SIZE, (uint8_t*) &(result[0]));
+ return result;
+#else
const uint64_t* values = (const uint64_t*) data;
size_t n = xbt_pagesize / sizeof(uint64_t);
hash = ((hash << 5) + hash) + values[i];
}
return hash;
+#endif
}
// ***** snapshot_page_manager
{
this->free_pages_.push_back(pageno);
const void* page = this->get_page(pageno);
- uint64_t hash = mc_hash_page(page);
+ hash_type hash = mc_hash_page(page);
+#ifdef MC_PAGE_STORE_MD4
+ this->hash_index_.erase(hash);
+#else
this->hash_index_[hash].erase(pageno);
+#endif
}
/** Store a page in memory */
size_t s_mc_pages_store::store_page(void* page)
{
- xbt_assert(mc_page_offset(page)==0, "Not at the beginning of a page");
xbt_assert(top_index_ <= this->capacity_, "top_index is not consistent");
// First, we check if a page with the same content is already in the page
// 1. compute the hash of the page;
// 2. find pages with the same hash using `hash_index_`;
// 3. find a page with the same content.
- uint64_t hash = mc_hash_page(page);
+ hash_type hash = mc_hash_page(page);
+#ifdef MC_PAGE_STORE_MD4
+ s_mc_pages_store::pages_map_type::const_iterator i =
+ this->hash_index_.find(hash);
+ if (i!=this->hash_index_.cend()) {
+ // If a page with the same content is already in the page store it is
+ // reused and its reference count is incremented.
+ size_t pageno = i->second;
+ page_counts_[pageno]++;
+ return pageno;
+ }
+#else
+
+ // Try to find a duplicate in set of pages with the same hash:
page_set_type& page_set = this->hash_index_[hash];
BOOST_FOREACH (size_t pageno, page_set) {
const void* snapshot_page = this->get_page(pageno);
}
}
+#endif
// Otherwise, a new page is allocated in the page store and the content
// of the page is `memcpy()`-ed to this new page.
xbt_assert(this->page_counts_[pageno]==0, "Allocated page is already used");
void* snapshot_page = (void*) this->get_page(pageno);
memcpy(snapshot_page, page, xbt_pagesize);
+#ifdef MC_PAGE_STORE_MD4
+ this->hash_index_[hash] = pageno;
+#else
page_set.insert(pageno);
+#endif
page_counts_[pageno]++;
return pageno;
}
return new s_mc_pages_store_t(500);
}
+void mc_pages_store_delete(mc_pages_store_t store)
+{
+ delete store;
+}
+
+}
+
+#ifdef SIMGRID_TEST
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+#include <memory>
+
+#include "mc/mc_page_store.h"
+
+static int value = 0;
+
+static void new_content(void* data, size_t size)
+{
+ memset(data, ++value, size);
+}
+
+static void* getpage()
+{
+ return mmap(NULL, getpagesize(), PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+}
+
+extern "C" {
+
+XBT_TEST_SUITE("mc_page_store", "Page store");
+
+XBT_TEST_UNIT("base", test_mc_page_store, "Test adding/removing pages in the store")
+{
+ xbt_test_add("Init");
+ size_t pagesize = (size_t) getpagesize();
+ std::auto_ptr<s_mc_pages_store_t> store = std::auto_ptr<s_mc_pages_store_t>(new s_mc_pages_store(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 */
