1 /* Copyright (c) 2014. The SimGrid Team.
2 * All rights reserved. */
4 /* This program is free software; you can redistribute it and/or modify it
5 * under the terms of the license (GNU LGPL) which comes with this package. */
8 #include <string.h> // memcpy, memcp
10 #include <boost/foreach.hpp>
14 #include "mc_page_store.h"
18 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_page_snapshot, mc,
19 "Logging specific to mc_page_snapshot");
23 static void mc_read_pagemap(uint64_t* pagemap, size_t page_start, size_t page_count);
29 /** @brief Compte a hash for the given memory page
31 * The page is used before inserting the page in the page store
32 * in order to find duplicate of this pae in the page store.
34 * @param data Memory page
35 * @return hash off the page
37 static inline uint64_t mc_hash_page(const void* data)
39 const uint64_t* values = (const uint64_t*) data;
40 size_t n = xbt_pagesize / sizeof(uint64_t);
44 for (size_t i=0; i!=n; ++i) {
45 hash = ((hash << 5) + hash) + values[i];
50 // ***** snapshot_page_manager
52 s_mc_pages_store::s_mc_pages_store(size_t size) :
53 memory_(NULL), capacity_(0), top_index_(0)
55 // Using mmap in order to be able to expand the region
56 // by relocating it somewhere else in the virtual memory
58 void * memory = ::mmap(NULL, size << xbt_pagebits, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS|MAP_POPULATE, -1, 0);
59 if (memory==MAP_FAILED) {
60 xbt_die("Could not mmap initial snapshot pages.");
64 this->capacity_ = size;
65 this->memory_ = memory;
66 this->page_counts_.resize(size);
69 s_mc_pages_store::~s_mc_pages_store()
71 ::munmap(this->memory_, this->capacity_ << xbt_pagebits);
74 void s_mc_pages_store::resize(size_t size)
76 size_t new_bytesize = size << xbt_pagebits;
78 // Expand the memory region by moving it into another
79 // virtual memory address if necessary:
80 void* new_memory = mremap(this->memory_, this->capacity_ << xbt_pagesize, new_bytesize, MREMAP_MAYMOVE);
81 if (new_memory == MAP_FAILED) {
82 xbt_die("Could not mremap snapshot pages.");
85 this->capacity_ = size;
86 this->memory_ = new_memory;
87 this->page_counts_.resize(size);
90 /** Allocate a free page
92 * @return index of the free page
94 size_t s_mc_pages_store::alloc_page()
96 if (this->free_pages_.empty()) {
99 if (top_index_ == this->capacity_) {
100 // All the pages are allocated, we need add more pages:
101 this->resize(2 * this->capacity_);
104 // Use a page from the top:
105 return this->top_index_++;
109 // Use a page from free_pages_ (inside of the region):
110 size_t res = this->free_pages_[this->free_pages_.size() - 1];
111 this->free_pages_.pop_back();
117 void s_mc_pages_store::remove_page(size_t pageno)
119 this->free_pages_.push_back(pageno);
120 void* page = mc_page_from_number(this->memory_, pageno);
121 uint64_t hash = mc_hash_page(page);
122 this->hash_index_[hash].erase(pageno);
125 /** Store a page in memory */
126 size_t s_mc_pages_store::store_page(void* page)
128 xbt_assert(mc_page_offset(page)==0, "Not at the beginning of a page");
129 xbt_assert(top_index_ <= this->capacity_, "top_index is not consistent");
131 // Search the page in the snapshot pages:
132 uint64_t hash = mc_hash_page(page);
133 page_set_type& page_set = this->hash_index_[hash];
134 BOOST_FOREACH (size_t pageno, page_set) {
135 const void* snapshot_page = this->get_page(pageno);
136 if (memcmp(page, snapshot_page, xbt_pagesize) == 0) {
137 // Page found, reuse it:
138 page_counts_[pageno]++;
143 // Allocate a new page for this page:
144 size_t pageno = alloc_page();
145 void* snapshot_page = (void*) this->get_page(pageno);
146 memcpy(snapshot_page, page, xbt_pagesize);
147 page_set.insert(pageno);
148 page_counts_[pageno]++;
156 mc_pages_store_t mc_pages_store_new()
158 return new s_mc_pages_store_t(500);