#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 */
// 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;
}
#ifdef __cplusplus
#include <vector>
+#include <boost/array.hpp>
#include <boost/utility.hpp>
#include <boost/unordered_map.hpp>
#include <boost/unordered_set.hpp>
*
*/
struct s_mc_pages_store {
-private: // Types
+public: // Types
+#ifdef MC_PAGE_STORE_MD4
+ typedef boost::array<uint64_t,2> hash_type;
+#else
typedef uint64_t hash_type;
- typedef boost ::unordered_set<size_t> page_set_type;
+#endif
+private: // Types
+#ifdef MC_PAGE_STORE_MD4
+ // We are using a secure hash to identify a page.
+ // We assume there will not be any collision: we need to map a hash
+ // to a single page index.
+ typedef boost::unordered_map<hash_type, size_t> pages_map_type;
+#else
+ // We are using a cheap hash to index a page.
+ // We should expect collision and we need to associate multiple page indices
+ // to the same hash.
+ typedef boost::unordered_set<size_t> page_set_type;
typedef boost::unordered_map<hash_type, page_set_type> pages_map_type;
+#endif
private: // Fields:
/** First page
