[mc] Rename PerPageCopy to ChunkedData (and move in its own files)

[simgrid.git] / src / mc / ChunkedData.cpp

diff --git a/src/mc/ChunkedData.cpp b/src/mc/ChunkedData.cpp
new file mode 100644 (file)
index 0000000..c1f3e2d
--- /dev/null
+++ b/src/mc/ChunkedData.cpp
@@ -0,0 +1,54 @@
+#include <mc/ChunkedData.hpp>
+
+#define SOFT_DIRTY_BIT_NUMBER 55
+#define SOFT_DIRTY (((uint64_t)1) << SOFT_DIRTY_BIT_NUMBER)
+
+namespace simgrid {
+namespace mc {
+
+/** 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
+ *  @return                Snapshot page numbers of this new snapshot
+ */
+ChunkedData::ChunkedData(PageStore& store, AddressSpace& as,
+    remote_ptr<void> addr, std::size_t page_count,
+    const std::size_t* ref_page_numbers, const std::uint64_t* pagemap)
+{
+  store_ = &store;
+  this->pagenos_.resize(page_count);
+  std::vector<char> buffer(xbt_pagesize);
+
+  for (size_t i = 0; i != page_count; ++i) {
+
+    // We don't have to compare soft-clean pages:
+    if (ref_page_numbers && pagemap && !(pagemap[i] & SOFT_DIRTY)) {
+      pagenos_[i] = ref_page_numbers[i];
+      store_->ref_page(ref_page_numbers[i]);
+      continue;
+    }
+
+      remote_ptr<void> page = remote(addr.address() + (i << xbt_pagebits));
+      xbt_assert(mc_page_offset((void*)page.address())==0,
+        "Not at the beginning of a page");
+
+        /* Adding another copy (and a syscall) will probably slow things a lot.
+           TODO, optimize this somehow (at least by grouping the syscalls)
+           if needed. Either:
+            - reduce the number of syscalls;
+            - let the application snapshot itself;
+            - move the segments in shared memory (this will break `fork` however).
+        */
+
+        as.read_bytes(
+          buffer.data(), xbt_pagesize, page,
+          simgrid::mc::ProcessIndexDisabled);
+
+      pagenos_[i] = store_->store_page(buffer.data());
+
+  }
+}
+
+}
+}