X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/fe304706848f0a64477d4687b3ea97d5b9a0c35c..HEAD:/src/mc/sosp/PageStore.cpp diff --git a/src/mc/sosp/PageStore.cpp b/src/mc/sosp/PageStore.cpp deleted file mode 100644 index 6cb9b5e5d9..0000000000 --- a/src/mc/sosp/PageStore.cpp +++ /dev/null @@ -1,176 +0,0 @@ -/* Copyright (c) 2015-2019. 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 -#ifdef __FreeBSD__ -#define MAP_POPULATE MAP_PREFAULT_READ -#endif - -#include "src/internal_config.h" -#include "xbt/log.h" -#include "xbt/sysdep.h" - -#include "src/mc/sosp/PageStore.hpp" -#include "src/mc/mc_mmu.hpp" - -#include // memcpy, memcmp -#include - -XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_page_snapshot, mc, "Logging specific to mc_page_snapshot"); - -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. - * - * @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; -} - -// ***** snapshot_page_manager - -PageStore::PageStore(std::size_t size) : memory_(nullptr), capacity_(size), top_index_(0) -{ - // Using mmap in order to be able to expand the region by relocating it somewhere else in the virtual memory space: - void* memory = - ::mmap(nullptr, size << xbt_pagebits, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, -1, 0); - if (memory == MAP_FAILED) - xbt_die("Could not mmap initial snapshot pages."); - - this->top_index_ = 0; - this->memory_ = memory; - this->page_counts_.resize(size); -} - -PageStore::~PageStore() -{ - ::munmap(this->memory_, this->capacity_ << xbt_pagebits); -} - -void PageStore::resize(std::size_t size) -{ - size_t old_bytesize = this->capacity_ << xbt_pagebits; - size_t new_bytesize = size << xbt_pagebits; - void* new_memory; - - // Expand the memory region by moving it into another - // virtual memory address if necessary: -#if HAVE_MREMAP - new_memory = mremap(this->memory_, old_bytesize, new_bytesize, MREMAP_MAYMOVE); - if (new_memory == MAP_FAILED) - xbt_die("Could not mremap snapshot pages."); -#else - if (new_bytesize > old_bytesize) { - // Grow: first try to add new space after current map - new_memory = mmap((char*)this->memory_ + old_bytesize, new_bytesize - old_bytesize, PROT_READ | PROT_WRITE, - MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, -1, 0); - if (new_memory == MAP_FAILED) - xbt_die("Could not mremap snapshot pages."); - // 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 - 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); - if (new_memory == MAP_FAILED) - xbt_die("Could not mremap snapshot pages."); - memcpy(new_memory, this->memory_, old_bytesize); - munmap(this->memory_, old_bytesize); - } - } else { - // We don't have functions to shrink a mapping, so leave memory as - // it is for now - new_memory = this->memory_; - } -#endif - - this->capacity_ = size; - this->memory_ = new_memory; - this->page_counts_.resize(size, 0); -} - -/** Allocate a free page - * - * @return index of the free page - */ -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: - this->resize(2 * this->capacity_); - - // 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(); - return res; - } -} - -void PageStore::remove_page(std::size_t pageno) -{ - this->free_pages_.push_back(pageno); - const void* page = this->get_page(pageno); - hash_type hash = mc_hash_page(page); - this->hash_index_[hash].erase(pageno); -} - -/** Store a page in memory */ -std::size_t PageStore::store_page(void* 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 store: - // 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 - hash_type hash = mc_hash_page(page); - - // Try to find a duplicate in set of pages with the same hash: - page_set_type& page_set = this->hash_index_[hash]; - 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); - memcpy(snapshot_page, page, xbt_pagesize); - page_set.insert(pageno); - page_counts_[pageno]++; - return pageno; -} - -} // namespace mc -} // namespace simgrid