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8240868: Shenandoah: remove CM-with-UR piggybacking cycles

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Reviewed-by: rkennke, zgu
This commit is contained in:
Aleksey Shipilev 2020-03-11 14:17:52 +01:00
parent d778097371
commit eb974fad6d
15 changed files with 23 additions and 229 deletions
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34
src/hotspot/share/gc/shenandoah/shenandoahControlThread.cpp
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@ -316,19 +316,18 @@ void ShenandoahControlThread::service_concurrent_normal_cycle(GCCause::Cause cau
// If second allocation failure happens during Degenerated GC cycle (for example, when GC
// tries to evac something and no memory is available), cycle degrades to Full GC.
//
// There are also two shortcuts through the normal cycle: a) immediate garbage shortcut, when
// There are also a shortcut through the normal cycle: immediate garbage shortcut, when
// heuristics says there are no regions to compact, and all the collection comes from immediately
// reclaimable regions; b) coalesced UR shortcut, when heuristics decides to coalesce UR with the
// mark from the next cycle.
// reclaimable regions.
//
// ................................................................................................
//
// (immediate garbage shortcut) Concurrent GC
// /-------------------------------------------\
// | (coalesced UR) v
// | /----------------------->o
// | | |
// | | v
// | |
// | |
// | |
// | v
// [START] ----> Conc Mark ----o----> Conc Evac --o--> Conc Update-Refs ---o----> [END]
// | | | ^
// | (af) | (af) | (af) |
@ -392,22 +391,15 @@ void ShenandoahControlThread::service_concurrent_normal_cycle(GCCause::Cause cau
heap->entry_evac();
if (check_cancellation_or_degen(ShenandoahHeap::_degenerated_evac)) return;
// Perform update-refs phase, if required. This phase can be skipped if heuristics
// decides to piggy-back the update-refs on the next marking cycle. On either path,
// we need to turn off evacuation: either in init-update-refs, or in final-evac.
if (heap->heuristics()->should_start_update_refs()) {
heap->vmop_entry_init_updaterefs();
heap->entry_updaterefs();
if (check_cancellation_or_degen(ShenandoahHeap::_degenerated_updaterefs)) return;
// Perform update-refs phase.
heap->vmop_entry_init_updaterefs();
heap->entry_updaterefs();
if (check_cancellation_or_degen(ShenandoahHeap::_degenerated_updaterefs)) return;
heap->vmop_entry_final_updaterefs();
heap->vmop_entry_final_updaterefs();
// Update references freed up collection set, kick the cleanup to reclaim the space.
heap->entry_cleanup();
} else {
heap->vmop_entry_final_evac();
}
// Update references freed up collection set, kick the cleanup to reclaim the space.
heap->entry_cleanup();
}
// Cycle is complete