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[native] Investigation: GC bridge gref churn is not the cause of CoreCLR ART GC regression (informational, do not merge) #12263

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[native] Investigation: GC bridge gref churn is not the cause of CoreCLR ART GC regression (informational, do not merge) #12263

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11 changes: 11 additions & 0 deletions src/native/clr/host/bridge-processing.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -165,6 +165,17 @@ void BridgeProcessingShared::process () noexcept
GCBridge::trigger_java_gc (env);
cleanup_after_java_collection ();
log_gc_summary ();

// GC bridge gref churn instrumentation (dotnet/runtime#131370): one line per round.
// Every peer is flipped strong->weak in prepare (NewWeakGlobalRef + DeleteGlobalRef) and
// weak->strong in cleanup (NewGlobalRef + DeleteWeakGlobalRef): 4 JNI global-ref ops per peer.
size_t churn_peers = 0;
for (size_t i = 0; i < cross_refs->ComponentCount; i++) {
churn_peers = Helpers::add_with_overflow_check<size_t> (churn_peers, cross_refs->Components [i].Count);
}
log_warnf (LOG_GC, "GCBRIDGE_CHURN runtime=coreclr sccs=%zu peers=%zu xrefs=%zu jni_transitions=%zu",
static_cast<size_t> (cross_refs->ComponentCount), churn_peers,
static_cast<size_t> (cross_refs->CrossReferenceCount), churn_peers * 4);
}

void BridgeProcessingShared::prepare_for_java_collection () noexcept
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9 changes: 9 additions & 0 deletions src/native/mono/monodroid/osbridge.cc
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Expand Up @@ -1035,6 +1035,15 @@ OSBridge::gc_cross_references (int num_sccs, MonoGCBridgeSCC **sccs, int num_xre

gc_cleanup_after_java_collection (env, num_sccs, sccs);
set_bridge_processing_field (domains_list, 0);

// GC bridge gref churn instrumentation (dotnet/runtime#131370): one line per round.
// Every peer is flipped strong->weak in prepare (NewWeakGlobalRef + DeleteGlobalRef) and
// weak->strong in cleanup (NewGlobalRef + DeleteWeakGlobalRef): 4 JNI global-ref ops per peer.
int churn_peers = 0;
for (int i = 0; i < num_sccs; i++)
churn_peers += sccs [i]->num_objs;
log_warn (LOG_GC, "GCBRIDGE_CHURN runtime=mono sccs={} peers={} xrefs={} jni_transitions={}",
num_sccs, churn_peers, num_xrefs, churn_peers * 4);
}

void
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