tree c0efc03e357ad149627a0db74e23d0547e826b3a
parent dafde14e08ddfda747aabb2045b350848b601b2e
author Jason Evans <je@facebook.com> 1268969800 -0700
committer Jason Evans <je@facebook.com> 1268969800 -0700

Track dirty and clean runs separately.

Split arena->runs_avail into arena->runs_avail_{clean,dirty}, and
preferentially allocate dirty runs.