/** Take a per-page snapshot of a region
*
* @param addr The start of the region (must be at the beginning of a page)
* @param page_count Number of pages of the region
* @return Snapshot page numbers of this new snapshot
*/
ChunkedData::ChunkedData(PageStore& store, AddressSpace& as, RemotePtr<void> addr, std::size_t page_count)
{
store_ = &store;
this->pagenos_.resize(page_count);
std::vector<char> buffer(xbt_pagesize);
for (size_t i = 0; i != page_count; ++i) {
RemotePtr<void> page = remote((void*)simgrid::mc::mmu::join(i, addr.address()));
xbt_assert(simgrid::mc::mmu::split(page.address()).second == 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());
}
}
bool operator==(RemotePtr<X> const& x, RemotePtr<Y> const& y)
{
return x.address() == y.address();
}