Try push: https://treeherder.mozilla.org/#/jobs?repo=try&group_state=expanded&revision=8707c76c267fec042a9842321562d42482cdd0bb
try push shows the results of reducing chunks across the board:
in the baseline push, ccov builds appear to have uneven chunking with some chunks going over the 30 minute soft rule, and other chunks running for only 10 minutes.
the goal was to reduce the chunks from 8 to a manageable 5, in the hopes that some faster chunks are merged together. The shorter chunks are combined, but at the same time the longer chunks also take correspondingly longer time to run.
chunk count remains at 1, as it currently stands. Runtime of these single-chunk xpcshelltest sometimes exceed 30 minutes, sometimes under 30 minutes. Considering the current baseline also sees the same behavior, this is not a concern.
linux32 and linux64 had its chunk count reduced greatly, from 8 or 12 to 4 across the board.
For most of the linux runs the
X4 chunk appears to take the longest, in some cases (
linux64 opt) exceeding 45 minutes. Despite this I don't think this is cause for concern since even on the baseline,
linux64 opt takes 40 minutes, so the extra 5 minutes consumed in the reduced chunk is easily made up by savings from reduced overhead.