Expand PerfContext to add ss_file reads and serialized_reads.

db/version_set.cc

@@ -2521,9 +2521,19 @@ void Version::MultiGet(const ReadOptions& read_options, MultiGetRange* range,
  if (fp.GetHitFileLevel() == 0) {
  dump_stats_for_l0_file = true;
  }
+ // RocksDB-Cloud contribution begin
+ PERF_COUNTER_ADD(multiget_sst_file_read_count, 1);
+ // RocksDB-Cloud contribution end
  }
  if (s.ok()) {
  f = fp.GetNextFileInLevel();
+ // RocksDB-Cloud contribution begin
+ if (f) {
+ // We have another file to read. This implies that the read on 
+ // this file was blocked (or serialized) behind the previous read.
+ PERF_COUNTER_ADD(multiget_sst_serialized_file_read_count, 1);
+ }
+ // RocksDB-Cloud contribution end
  }
 #if USE_COROUTINES
  } else {
@@ -2567,6 +2577,9 @@ void Version::MultiGet(const ReadOptions& read_options, MultiGetRange* range,
  if (mget_tasks.size() > 0) {
  RecordTick(db_statistics_, MULTIGET_COROUTINE_COUNT,
  mget_tasks.size());
+ // RocksDB-Cloud contribution begin
+ PERF_COUNTER_ADD(multiget_sst_file_read_count, mget_tasks.size());
+ // RocksDB-Cloud contribution end
  // Collect all results so far
  std::vector<Status> statuses = folly::coro::blockingWait(
  folly::coro::collectAllRange(std::move(mget_tasks))
@@ -2582,6 +2595,13 @@ void Version::MultiGet(const ReadOptions& read_options, MultiGetRange* range,
 
  if (s.ok() && fp.KeyMaySpanNextFile()) {
  f = fp.GetNextFileInLevel();
+ // RocksDB-Cloud contribution begin
+ if (f) {
+ // We couldn't read all the files in this level 'in one go'.
+ // Record the number of files that were waiting.
+ PERF_COUNTER_ADD(multiget_sst_serialized_file_read_count, 1);
+ }
+ // RocksDB-Cloud contribution end
  }
  }
 #endif // USE_COROUTINES
@@ -2763,6 +2783,9 @@ Status Version::ProcessBatch(
  table_handle, std::get<0>(stat->second),
  std::get<1>(stat->second),
  std::get<2>(stat->second));
+ // RocksDB-Cloud contribution begin
+ PERF_COUNTER_ADD(multiget_sst_file_read_count, mget_iter.size());
+ // RocksDB-Cloud contribution end
  } else {
  mget_tasks.emplace_back(MultiGetFromSSTCoroutine(
  read_options, file_range, fp.GetHitFileLevel(), skip_filters,
@@ -2853,6 +2876,9 @@ Status Version::MultiGetAsync(
  if (mget_tasks.size() > 0) {
  assert(waiting.size());
  RecordTick(db_statistics_, MULTIGET_COROUTINE_COUNT, mget_tasks.size());
+ // RocksDB-Cloud contribution begin
+ PERF_COUNTER_ADD(multiget_sst_file_read_count, mget_tasks.size());
+ // RocksDB-Cloud contribution end
  // Collect all results so far
  std::vector<Status> statuses = folly::coro::blockingWait(
  folly::coro::collectAllRange(std::move(mget_tasks))
@@ -2879,6 +2905,13 @@ Status Version::MultiGetAsync(
  // and no need to prepare the next level.
  if (!fp.GetHitFile() && !fp.GetRange().empty()) {
  fp.PrepareNextLevelForSearch();
+ } else {
+ // RocksDB-Cloud contribution begin
+ // We still need to read files in the current level despite running
+ // some rounds of coroutine parallel reads. Record the fact that 
+ // file reads were serialized.
+ PERF_COUNTER_ADD(multiget_sst_serialized_file_read_count, 1);
+ // RocksDB-Cloud contribution end
  }
  }
  to_process.swap(waiting);

include/rocksdb/perf_context.h

@@ -80,6 +80,15 @@ struct PerfContext {
  uint64_t filter_block_read_count; // total number of filter block reads
  uint64_t compression_dict_block_read_count; // total number of compression
  // dictionary block reads
+
+ // RocksDB-Cloud contribution begin
+
+ // Total number of files read in MultiGet operations
+ uint64_t multiget_sst_file_read_count;
+ // Number of times file reads were serialized behind other reads
+ uint64_t multiget_sst_serialized_file_read_count;
+
+ // RocksDB-Cloud contribution end
 
  uint64_t secondary_cache_hit_count; // total number of secondary cache hits
  // total number of real handles inserted into secondary cache

monitoring/perf_context.cc

@@ -43,6 +43,13 @@ PerfContext::PerfContext(const PerfContext& other) {
  block_cache_filter_hit_count = other.block_cache_filter_hit_count;
  filter_block_read_count = other.filter_block_read_count;
  compression_dict_block_read_count = other.compression_dict_block_read_count;
+
+ // RocksDB-Cloud contribution begin
+ multiget_sst_file_read_count = other.multiget_sst_file_read_count;
+ multiget_sst_serialized_file_read_count = 
+ other.multiget_sst_serialized_file_read_count;
+ // RocksDB-Cloud contribution end
+
  secondary_cache_hit_count = other.secondary_cache_hit_count;
  compressed_sec_cache_insert_real_count =
  other.compressed_sec_cache_insert_real_count;
@@ -162,6 +169,13 @@ PerfContext::PerfContext(PerfContext&& other) noexcept {
  block_cache_filter_hit_count = other.block_cache_filter_hit_count;
  filter_block_read_count = other.filter_block_read_count;
  compression_dict_block_read_count = other.compression_dict_block_read_count;
+
+ // RocksDB-Cloud contribution begin
+ multiget_sst_file_read_count = other.multiget_sst_file_read_count;
+ multiget_sst_serialized_file_read_count = 
+ other.multiget_sst_serialized_file_read_count;
+ // RocksDB-Cloud contribution end
+
  secondary_cache_hit_count = other.secondary_cache_hit_count;
  compressed_sec_cache_insert_real_count =
  other.compressed_sec_cache_insert_real_count;
@@ -283,6 +297,13 @@ PerfContext& PerfContext::operator=(const PerfContext& other) {
  block_cache_filter_hit_count = other.block_cache_filter_hit_count;
  filter_block_read_count = other.filter_block_read_count;
  compression_dict_block_read_count = other.compression_dict_block_read_count;
+
+ // RocksDB-Cloud contribution begin
+ multiget_sst_file_read_count = other.multiget_sst_file_read_count;
+ multiget_sst_serialized_file_read_count = 
+ other.multiget_sst_serialized_file_read_count;
+ // RocksDB-Cloud contribution end
+
  secondary_cache_hit_count = other.secondary_cache_hit_count;
  compressed_sec_cache_insert_real_count =
  other.compressed_sec_cache_insert_real_count;
@@ -400,6 +421,12 @@ void PerfContext::Reset() {
  block_cache_filter_hit_count = 0;
  filter_block_read_count = 0;
  compression_dict_block_read_count = 0;
+
+ // RocksDB-Cloud contribution begin
+ multiget_sst_file_read_count = 0;
+ multiget_sst_serialized_file_read_count = 0;
+ // RocksDB-Cloud contribution end
+
  secondary_cache_hit_count = 0;
  compressed_sec_cache_insert_real_count = 0;
  compressed_sec_cache_insert_dummy_count = 0;
@@ -536,6 +563,12 @@ std::string PerfContext::ToString(bool exclude_zero_counters) const {
  PERF_CONTEXT_OUTPUT(block_cache_filter_hit_count);
  PERF_CONTEXT_OUTPUT(filter_block_read_count);
  PERF_CONTEXT_OUTPUT(compression_dict_block_read_count);
+
+ // RocksDB-Cloud contribution begin
+ PERF_CONTEXT_OUTPUT(multiget_sst_file_read_count);
+ PERF_CONTEXT_OUTPUT(multiget_sst_serialized_file_read_count);
+ // RocksDB-Cloud contribution end
+
  PERF_CONTEXT_OUTPUT(secondary_cache_hit_count);
  PERF_CONTEXT_OUTPUT(compressed_sec_cache_insert_real_count);
  PERF_CONTEXT_OUTPUT(compressed_sec_cache_insert_dummy_count);