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[wip] Fix aggression factor #16

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[wip] Fix aggression factor #16

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400ac4f
Reset inc_failure_count whenever below target, not just if decreasing…
markples Feb 22, 2024
7961d63
Limit inc_failure_count to 2 and ignore it after 40 GCs
markples Feb 22, 2024
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24 changes: 14 additions & 10 deletions src/coreclr/gc/gc.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -25492,10 +25492,14 @@ int gc_heap::calculate_new_heap_count ()
{
if (((int)dynamic_heap_count_data.last_changed_count > 0) && (dynamic_heap_count_data.last_changed_gc_index > 0.0))
{
(dynamic_heap_count_data.inc_failure_count)++;
dprintf (6666, ("[CHP0-4] just grew %d GCs ago, grow more aggressively from %d -> %d more heaps",
(current_gc_index - dynamic_heap_count_data.last_changed_gc_index), step_up_int, (step_up_int * (dynamic_heap_count_data.inc_failure_count + 1))));
step_up_int *= dynamic_heap_count_data.inc_failure_count + 1;
size_t gc_count_since_last_growth = (current_gc_index - dynamic_heap_count_data.last_changed_gc_index);
if (gc_count_since_last_growth <= dynamic_heap_count_data.inc_failure_gcs_threshold)
{
dynamic_heap_count_data.inc_failure_count = min(dynamic_heap_count_data.inc_failure_count + 1, dynamic_heap_count_data.inc_failure_limit);
dprintf (6666, ("[CHP0-4] just grew %d GCs ago, grow more aggressively from %d -> %d more heaps",
gc_count_since_last_growth, step_up_int, (step_up_int * (dynamic_heap_count_data.inc_failure_count + 1))));
step_up_int *= dynamic_heap_count_data.inc_failure_count + 1;
}
}
}
}
Expand Down Expand Up @@ -25650,19 +25654,19 @@ int gc_heap::calculate_new_heap_count ()
dynamic_heap_count_data.below_target_accumulation = 0;
}

if (dynamic_heap_count_data.inc_failure_count)
{
dprintf (6666, ("[CHP1] shrink, reset inc failure count (was %d)", dynamic_heap_count_data.inc_failure_count));
dynamic_heap_count_data.inc_failure_count = 0;
}

if (new_n_heaps < n_heaps)
{
dynamic_heap_count_data.last_changed_gc_index = current_gc_index;
dynamic_heap_count_data.last_changed_count = (float)(new_n_heaps - n_heaps);
dynamic_heap_count_data.last_changed_stcp = smoothed_median_throughput_cost_percent;
dprintf (6666, ("[CHP1] setting last changed gc index to %Id, count to %.3f, stcp to %.3f",
dynamic_heap_count_data.last_changed_gc_index, dynamic_heap_count_data.last_changed_count, dynamic_heap_count_data.last_changed_stcp));

if (dynamic_heap_count_data.inc_failure_count)
{
dprintf (6666, ("[CHP1] shrink, reset inc failure count (was %d)", dynamic_heap_count_data.inc_failure_count));
dynamic_heap_count_data.inc_failure_count = 0;
}
}
}
}
Expand Down
5 changes: 4 additions & 1 deletion src/coreclr/gc/gcpriv.h
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Expand Up @@ -4339,8 +4339,11 @@ class gc_heap
// For tuning above/below target tcp.
//
// If we just increased the heap count and immediately need to grow again, that counts as a failure.
// The higher the failure count, the more aggressive we should grow.
// The higher the failure count, the more aggressive we should grow, but only to a point.
int inc_failure_count;
const int inc_failure_limit = 2;
// After enough GCs without growth, we should stop being aggressive due to the failure count.
const int inc_failure_gcs_threshold = 40;

// If we are trending up and the tcp is already close enough to target, we need this many samples
// before we adjust.
Expand Down