X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/3374b0b6c5c0f9eee3083f513f8a793ec3556067..475eb62ac657b1f90903930e170369175278ab19:/src/mc/mc_page_snapshot.cpp diff --git a/src/mc/mc_page_snapshot.cpp b/src/mc/mc_page_snapshot.cpp index 549101acbb..2d095213af 100644 --- a/src/mc/mc_page_snapshot.cpp +++ b/src/mc/mc_page_snapshot.cpp @@ -1,5 +1,8 @@ #include "mc_page_store.h" #include "mc_mmu.h" +#include "mc_private.h" + +#include #define SOFT_DIRTY_BIT_NUMBER 55 #define SOFT_DIRTY (((uint64_t)1) << SOFT_DIRTY_BIT_NUMBER) @@ -8,13 +11,21 @@ extern "C" { // ***** Region management: +/** @brief Take a per-page snapshot of a region + * + * @param data The start of the region (must be at the beginning of a page) + * @param pag_count Number of pages of the region + * @param pagemap Linux kernel pagemap values fot this region (or NULL) + * @param reference_pages Snapshot page numbers of the previous soft_dirty_reset (or NULL) + * @return Snapshot page numbers of this new snapshot + */ size_t* mc_take_page_snapshot_region(void* data, size_t page_count, uint64_t* pagemap, size_t* reference_pages) { size_t* pagenos = (size_t*) malloc(page_count * sizeof(size_t)); for (size_t i=0; i!=page_count; ++i) { bool softclean = pagemap && !(pagemap[i] & SOFT_DIRTY); - if (softclean) { + if (softclean && reference_pages) { // The page is softclean, it is the same page as the reference page: pagenos[i] = reference_pages[i]; mc_model_checker->pages->ref_page(reference_pages[i]); @@ -36,6 +47,16 @@ void mc_free_page_snapshot_region(size_t* pagenos, size_t page_count) } } +/** @brief Restore a snapshot of a region + * + * If possible, the restoration will be incremental + * (the modified pages will not be touched). + * + * @param data The start of the region (must be at the beginning of a page) + * @param pag_count Number of pages of the region + * @param pagemap Linux kernel pagemap values fot this region (or NULL) + * @param reference_pages Snapshot page numbers of the previous soft_dirty_reset (or NULL) + */ void mc_restore_page_snapshot_region(mc_mem_region_t region, size_t page_count, uint64_t* pagemap, mc_mem_region_t reference_region) { for (size_t i=0; i!=page_count; ++i) { @@ -67,14 +88,15 @@ static size_t pread_whole(int fd, void* buf, size_t count, off_t offset) { if (n==0) return res; - // Error (or EAGAIN): + // Error (or EINTR): if (n==-1) { - if (errno == EAGAIN) + if (errno == EINTR) continue; else return -1; } + // It might be a partial read: count -= n; data += n; offset += n; @@ -84,7 +106,8 @@ static size_t pread_whole(int fd, void* buf, size_t count, off_t offset) { return res; } -static inline void mc_ensure_fd(int* fd, const char* path, int flags) { +static inline __attribute__ ((always_inline)) +void mc_ensure_fd(int* fd, const char* path, int flags) { if (*fd != -1) return; *fd = open(path, flags); @@ -93,11 +116,13 @@ static inline void mc_ensure_fd(int* fd, const char* path, int flags) { } } -/** @brief Reset the softdirty bits +/** @brief Reset the soft-dirty bits * * This is done after checkpointing and after checkpoint restoration * (if per page checkpoiting is used) in order to know which pages were * modified. + * + * See https://www.kernel.org/doc/Documentation/vm/soft-dirty.txt * */ void mc_softdirty_reset() { mc_ensure_fd(&mc_model_checker->fd_clear_refs, "/proc/self/clear_refs", O_WRONLY|O_CLOEXEC); @@ -106,13 +131,16 @@ void mc_softdirty_reset() { } } -/** @brief Read /proc/self/pagemap informations in order to find properties on the pages +/** @brief Read memory page informations * - * For each virtual memory page, this file provides informations. + * For each virtual memory page of the process, + * /proc/self/pagemap provides a 64 bit field of information. * We are interested in the soft-dirty bit: with this we can track which * pages were modified between snapshots/restorations and avoid * copying data which was not modified. * + * See https://www.kernel.org/doc/Documentation/vm/pagemap.txt + * * @param pagemap Output buffer for pagemap informations * @param start_addr Address of the first page * @param page_count Number of pages @@ -143,8 +171,8 @@ mc_mem_region_t mc_region_new_sparse(int type, void *start_addr, size_t size, mc size_t page_count = mc_page_count(size); uint64_t* pagemap = NULL; - if (mc_model_checker->parent_snapshot) { - pagemap = (uint64_t*) alloca(sizeof(uint64_t) * page_count); + if (_sg_mc_soft_dirty && mc_model_checker->parent_snapshot) { + pagemap = (uint64_t*) mmalloc_no_memset((xbt_mheap_t) mc_heap, sizeof(uint64_t) * page_count); mc_read_pagemap(pagemap, mc_page_number(NULL, start_addr), page_count); } @@ -152,6 +180,9 @@ mc_mem_region_t mc_region_new_sparse(int type, void *start_addr, size_t size, mc new_reg->page_numbers = mc_take_page_snapshot_region(start_addr, page_count, pagemap, ref_reg==NULL ? NULL : ref_reg->page_numbers); + if(pagemap) { + mfree((xbt_mheap_t) mc_heap, pagemap); + } return new_reg; } @@ -164,13 +195,19 @@ void mc_region_restore_sparse(mc_mem_region_t reg, mc_mem_region_t ref_reg) uint64_t* pagemap = NULL; // Read soft-dirty bits if necessary in order to know which pages have changed: - if (mc_model_checker->parent_snapshot) { - pagemap = (uint64_t*) alloca(sizeof(uint64_t) * page_count); + if (_sg_mc_soft_dirty && mc_model_checker->parent_snapshot) { + pagemap = (uint64_t*) mmalloc_no_memset((xbt_mheap_t) mc_heap, sizeof(uint64_t) * page_count); mc_read_pagemap(pagemap, mc_page_number(NULL, reg->start_addr), page_count); } // Incremental per-page snapshot restoration: mc_restore_page_snapshot_region(reg, page_count, pagemap, ref_reg); + + // This is funny, the restoration can restore the state of the current heap, + // if this happen free(pagemap) would free from the wrong heap: + if(pagemap) { + mfree((xbt_mheap_t) mc_heap, pagemap); + } } }