Buildworld at r328519 has great difficulty finishing. It most often crashes
with 
panic: Assertion td->td_lock == TDQ_LOCKPTR(tdq) failed at /usr/src/sys/kern/sched_ule.c:2019 
but there have been a couple spontaneous reboots which left no trace.


Swap usage peaks around  1.3 GB out of 2 available with complaints of "out of
swap" but the system does not always crash.. No indication during boot of
excess swap allocation, so it's unclear why the extra 700M can't be used.

In at least one case, it appears the compiler crashed, stopping buildworkd,
but the kernel crashed anyway some hours (?) later.