It seems that mongos sys-perf tests are running a bit longer recently, and including the validate part, the mmapv1 task is at risk at hitting the 6 hour limit.

We should increase the exec_timeout_secs to 8 hours for that task. While doing that, please double check superficially that there isn't anything wrong why the task takes longer. (The assumption is that addition of fio and changing to EBS has made total runtime slower, even if the test results don't seem to have regressed.)