Open qinsoon opened 5 months ago
There are several possible reasons.
FreeListPageResource::release_pages
. Now it holds the mutex lock while (1) querying the free_list.size
, and (2) calling self.mprotect
(LOS only).Since the CI is not using PGO, the inlining decision is more likely to be the cause.
But the way MarkSweep sweeps block may be a bottleneck, too. MarkSweep executes SweepChunk in parallel, but whenever freeing any particular block, it needs to hold a mutex lock (even before https://github.com/mmtk/mmtk-core/pull/953).
We should look at the eBPF trace of MarkSweep to find its true inefficiency.
We see between 1% to 6% (pmd) slowndown in CI for OpenJDK after https://github.com/mmtk/mmtk-core/pull/953 (
hammer-2024-05-10-Fri-144600
).