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Fix distribute free regions #74916

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Merged
PeterSolMS merged 7 commits into from
Sep 29, 2022
Merged

Fix distribute free regions #74916

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f29ae9e
Make distributing free regions more precise so we know that each heap…
PeterSolMS Sep 1, 2022
8732c2d
Merge branch 'main' into Fix_distribute_free_regions
PeterSolMS Sep 1, 2022
53b9a0d
Change the computation of the budget correction per heap to distribut…
PeterSolMS Sep 5, 2022
b2a1945
Tweaks to distribute_free_regions: increase age to decommit for many …
PeterSolMS Sep 8, 2022
aa48fd0
Next refinement to distribute_free_regions: establish a minimum budge…
PeterSolMS Sep 15, 2022
4fbc950
Merge branch 'main' into Fix_distribute_free_regions
PeterSolMS Sep 28, 2022
f6b5c7e
Addressed code review feedback - min_heap_budget_in_region_units is t…
PeterSolMS Sep 28, 2022
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106 changes: 92 additions & 14 deletions src/coreclr/gc/gc.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12642,6 +12642,7 @@ void gc_heap::distribute_free_regions()
size_t num_decommit_regions_by_time = 0;
size_t size_decommit_regions_by_time = 0;
size_t heap_budget_in_region_units[MAX_SUPPORTED_CPUS][kind_count];
size_t min_heap_budget_in_region_units[MAX_SUPPORTED_CPUS];
size_t region_size[kind_count] = { global_region_allocator.get_region_alignment(), global_region_allocator.get_large_region_alignment() };
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@Maoni0 Maoni0 Sep 26, 2022

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since we are only using this for SOH, it seems like this can just be declared as

size_t min_heap_budget_in_region_units[MAX_SUPPORTED_CPUS];

MAX_SUPPORTED_CPUS is 1024 so this is quite a large data structure.

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@PeterSolMS PeterSolMS Sep 28, 2022

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Well, we are using it for UOH as well, but it's always 0 in this case, so we can use an if-statement or conditional expression.

I'll fix it...

region_free_list surplus_regions[kind_count];
for (int kind = basic_free_region; kind < kind_count; kind++)
Expand All @@ -12659,6 +12660,7 @@ void gc_heap::distribute_free_regions()
gc_heap* hp = pGenGCHeap;
// just to reduce the number of #ifdefs in the code below
const int i = 0;
const int n_heaps = 1;
#endif //MULTIPLE_HEAPS

for (int kind = basic_free_region; kind < kind_count; kind++)
Expand All @@ -12669,7 +12671,8 @@ void gc_heap::distribute_free_regions()
for (heap_segment* region = region_list.get_first_free_region(); region != nullptr; region = next_region)
{
next_region = heap_segment_next (region);
if (heap_segment_age_in_free (region) >= AGE_IN_FREE_TO_DECOMMIT)
int age_in_free_to_decommit = min (max (AGE_IN_FREE_TO_DECOMMIT, n_heaps), MAX_AGE_IN_FREE);
if (heap_segment_age_in_free (region) >= age_in_free_to_decommit)
{
num_decommit_regions_by_time++;
size_decommit_regions_by_time += get_region_committed_size (region);
Expand All @@ -12686,13 +12689,43 @@ void gc_heap::distribute_free_regions()
global_free_huge_regions.transfer_regions (&hp->free_regions[huge_free_region]);

heap_budget_in_region_units[i][basic_free_region] = 0;
min_heap_budget_in_region_units[i] = 0;
heap_budget_in_region_units[i][large_free_region] = 0;
for (int gen = soh_gen0; gen < total_generation_count; gen++)
}

for (int gen = soh_gen0; gen < total_generation_count; gen++)
{
if ((gen <= soh_gen2) &&
total_budget_in_region_units[basic_free_region] >= (total_num_free_regions[basic_free_region] +
surplus_regions[basic_free_region].get_num_free_regions()))
{
// don't accumulate budget from higher soh generations if we cannot cover lower ones
dprintf (REGIONS_LOG, ("out of free regions - skipping gen %d budget = %Id >= avail %Id",
gen,
total_budget_in_region_units[basic_free_region],
total_num_free_regions[basic_free_region] + surplus_regions[basic_free_region].get_num_free_regions()));
continue;
}
#ifdef MULTIPLE_HEAPS
for (int i = 0; i < n_heaps; i++)
{
gc_heap* hp = g_heaps[i];
#else //MULTIPLE_HEAPS
{
gc_heap* hp = pGenGCHeap;
// just to reduce the number of #ifdefs in the code below
const int i = 0;
const int n_heaps = 1;
#endif //MULTIPLE_HEAPS
ptrdiff_t budget_gen = max (hp->estimate_gen_growth (gen), 0);
int kind = gen >= loh_generation;
size_t budget_gen_in_region_units = (budget_gen + (region_size[kind] - 1)) / region_size[kind];
dprintf (REGIONS_LOG, ("h%2d gen %d has an estimated growth of %Id bytes (%Id regions)", i, gen, budget_gen, budget_gen_in_region_units));
if (gen <= soh_gen2)
{
// preserve the budget for the previous generation - we should not go below that
min_heap_budget_in_region_units[i] = heap_budget_in_region_units[i][kind];
}
heap_budget_in_region_units[i][kind] += budget_gen_in_region_units;
total_budget_in_region_units[kind] += budget_gen_in_region_units;
}
Expand Down Expand Up @@ -12742,15 +12775,54 @@ void gc_heap::distribute_free_regions()
{
dprintf (REGIONS_LOG, ("distributing the %Id %s regions deficit", -balance, kind_name[kind]));

#ifdef MULTIPLE_HEAPS
// we may have a deficit or - if background GC is going on - a surplus.
// adjust the budget per heap accordingly
ptrdiff_t adjustment_per_heap = (balance + (n_heaps - 1)) / n_heaps;

#ifdef MULTIPLE_HEAPS
for (int i = 0; i < n_heaps; i++)
if (balance != 0)
{
ptrdiff_t new_budget = (ptrdiff_t)heap_budget_in_region_units[i][kind] + adjustment_per_heap;
heap_budget_in_region_units[i][kind] = max (0, new_budget);
ptrdiff_t curr_balance = 0;
ptrdiff_t rem_balance = 0;
for (int i = 0; i < n_heaps; i++)
{
curr_balance += balance;
ptrdiff_t adjustment_per_heap = curr_balance / n_heaps;
curr_balance -= adjustment_per_heap * n_heaps;
ptrdiff_t new_budget = (ptrdiff_t)heap_budget_in_region_units[i][kind] + adjustment_per_heap;
ptrdiff_t min_budget = (kind == basic_free_region) ? (ptrdiff_t)min_heap_budget_in_region_units[i] : 0;
dprintf (REGIONS_LOG, ("adjusting the budget for heap %d from %Id %s regions by %Id to %Id",
i,
heap_budget_in_region_units[i][kind],
kind_name[kind],
adjustment_per_heap,
max (min_budget, new_budget)));
heap_budget_in_region_units[i][kind] = max (min_budget, new_budget);
rem_balance += new_budget - heap_budget_in_region_units[i][kind];
}
assert (rem_balance <= 0);
dprintf (REGIONS_LOG, ("remaining balance: %Id %s regions", rem_balance, kind_name[kind]));

// if we have a left over deficit, distribute that to the heaps that still have more than the minimum
while (rem_balance < 0)
{
for (int i = 0; i < n_heaps; i++)
{
size_t min_budget = (kind == basic_free_region) ? min_heap_budget_in_region_units[i] : 0;
if (heap_budget_in_region_units[i][kind] > min_budget)
{
dprintf (REGIONS_LOG, ("adjusting the budget for heap %d from %Id %s regions by %Id to %Id",
i,
heap_budget_in_region_units[i][kind],
kind_name[kind],
-1,
heap_budget_in_region_units[i][kind] - 1));

heap_budget_in_region_units[i][kind] -= 1;
rem_balance += 1;
if (rem_balance == 0)
break;
}
}
}
}
#endif //MULTIPLE_HEAPS
}
Expand Down Expand Up @@ -12802,11 +12874,12 @@ void gc_heap::distribute_free_regions()

if (hp->free_regions[kind].get_num_free_regions() > heap_budget_in_region_units[i][kind])
{
dprintf (REGIONS_LOG, ("removing %Id %s regions from heap %d with %Id regions",
dprintf (REGIONS_LOG, ("removing %Id %s regions from heap %d with %Id regions, budget is %Id",
hp->free_regions[kind].get_num_free_regions() - heap_budget_in_region_units[i][kind],
kind_name[kind],
i,
hp->free_regions[kind].get_num_free_regions()));
hp->free_regions[kind].get_num_free_regions(),
heap_budget_in_region_units[i][kind]));

remove_surplus_regions (&hp->free_regions[kind], &surplus_regions[kind], heap_budget_in_region_units[i][kind]);
}
Expand All @@ -12821,14 +12894,16 @@ void gc_heap::distribute_free_regions()
const int i = 0;
#endif //MULTIPLE_HEAPS

// second pass: fill all the regions having less than budget
if (hp->free_regions[kind].get_num_free_regions() < heap_budget_in_region_units[i][kind])
{
int64_t num_added_regions = add_regions (&hp->free_regions[kind], &surplus_regions[kind], heap_budget_in_region_units[i][kind]);
dprintf (REGIONS_LOG, ("added %Id %s regions to heap %d - now has %Id",
dprintf (REGIONS_LOG, ("added %Id %s regions to heap %d - now has %Id, budget is %Id",
num_added_regions,
kind_name[kind],
i,
hp->free_regions[kind].get_num_free_regions()));
hp->free_regions[kind].get_num_free_regions(),
heap_budget_in_region_units[i][kind]));
}
hp->free_regions[kind].sort_by_committed_and_age();
}
Expand Down Expand Up @@ -40561,9 +40636,12 @@ void gc_heap::decommit_ephemeral_segment_pages()
{
gradual_decommit_in_progress_p = TRUE;

dprintf (1, ("h%2d gen %d reduce_commit by %IdkB",
dprintf (1, ("h%2d gen %d region %Ix allocated %IdkB committed %IdkB reduce_commit by %IdkB",
heap_number,
gen_number,
get_region_start (tail_region),
(heap_segment_allocated (tail_region) - get_region_start (tail_region))/1024,
(heap_segment_committed (tail_region) - get_region_start (tail_region))/1024,
(heap_segment_committed (tail_region) - decommit_target)/1024));
}
dprintf(3, ("h%2d gen %d allocated: %IdkB committed: %IdkB target: %IdkB",
Expand Down Expand Up @@ -45068,7 +45146,7 @@ HRESULT GCHeap::Initialize()
gc_heap* hp = gc_heap::g_heaps[0];

dynamic_data* gen0_dd = hp->dynamic_data_of (0);
gc_heap::min_gen0_balance_delta = (dd_min_size (gen0_dd) >> 3);
gc_heap::min_gen0_balance_delta = (dd_min_size (gen0_dd) >> 6);

bool can_use_cpu_groups = GCToOSInterface::CanEnableGCCPUGroups();
GCConfig::SetGCCpuGroup(can_use_cpu_groups);
Expand Down