record for each swapin (previously, it was just at swapmod). The
reason for this is that as the testbed gets more fragmented in terms
of hardware, it is less and less likely that consecutive swapins of
the same experiment will use the same number of physical resources.

We end up with some duplication of data inside the table, but no big
deal. I suspect we will revisit this per experiment state as the
workbench stuff proceeds.