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dynamic delay: fix pending bytes rate calculation #451

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merged 1 commit into from
Apr 2, 2023
Merged

dynamic delay: fix pending bytes rate calculation #451

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20 changes: 8 additions & 12 deletions db/column_family.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -896,9 +896,8 @@ int GetL0ThresholdSpeedupCompaction(int level0_file_num_compaction_trigger,
} // namespace

namespace {
const uint64_t Gb = 1ull << 30;
const uint64_t Mb = 1ull << 20;
const int kMemtablePenalty = 10;
const int kNumPendingSteps = 100;
} // namespace

double ColumnFamilyData::TEST_CalculateWriteDelayDivider(
Expand Down Expand Up @@ -1001,21 +1000,18 @@ ColumnFamilyData::CalculateWriteDelayDividerAndMaybeUpdateWriteStallCause(
// Pending Compaction Bytes
double pending_divider = 1;
auto soft_limit = mutable_cf_options.soft_pending_compaction_bytes_limit;
if (soft_limit > 0 && compaction_needed_bytes >= soft_limit) {
if (soft_limit > 0 && compaction_needed_bytes > soft_limit) {
auto hard_limit = mutable_cf_options.hard_pending_compaction_bytes_limit;
// soft_limit != hard_limit here. we're in a kDelayed state here and not
// stop.
assert(hard_limit > soft_limit);
uint64_t soft_hard_range = hard_limit - soft_limit;
// change rate every 1G change or 100Mb if soft_hard_range is too small.
auto step_size = soft_hard_range > Gb ? Gb : 100 * Mb;
uint64_t num_steps = soft_hard_range / step_size;
auto extra_bytes = compaction_needed_bytes - soft_limit;
auto step_num = static_cast<uint64_t>(extra_bytes / step_size);
assert(step_num < num_steps);
if (num_steps > 0) {
pending_divider = 1 / (1 - (static_cast<double>(step_num) / num_steps));
}
uint64_t step_size = ceil(soft_hard_range / kNumPendingSteps);
uint64_t extra_bytes = compaction_needed_bytes - soft_limit;
uint64_t step_num = extra_bytes / step_size;
assert(step_num < kNumPendingSteps);
pending_divider =
1 / (1 - (static_cast<double>(step_num) / kNumPendingSteps));
}

double biggest_divider = 1;
Expand Down