Stream

Summary:
Add a simple policy for NVMe write time life hint
Closes https://github.com/facebook/rocksdb/pull/3095

Differential Revision: D6298030

Pulled By: shligit

fbshipit-source-id: 9a72a42e32e92193af11599eb71f0cf77448e24d

db/builder.cc

@@ -75,7 +75,7 @@ Status BuildTable(
     InternalStats* internal_stats, TableFileCreationReason reason,
     EventLogger* event_logger, int job_id, const Env::IOPriority io_priority,
     TableProperties* table_properties, int level, const uint64_t creation_time,
-    const uint64_t oldest_key_time) {
+    const uint64_t oldest_key_time, Env::WriteLifeTimeHint write_hint) {
   assert((column_family_id ==
           TablePropertiesCollectorFactory::Context::kUnknownColumnFamily) ==
          column_family_name.empty());
@@ -117,6 +117,7 @@ Status BuildTable(
         return s;
       }
       file->SetIOPriority(io_priority);
+      file->SetWriteLifeTimeHint(write_hint);
 
       file_writer.reset(new WritableFileWriter(std::move(file), env_options,
                                                ioptions.statistics));

db/builder.h

@@ -79,6 +79,7 @@ extern Status BuildTable(
     EventLogger* event_logger = nullptr, int job_id = 0,
     const Env::IOPriority io_priority = Env::IO_HIGH,
     TableProperties* table_properties = nullptr, int level = -1,
-    const uint64_t creation_time = 0, const uint64_t oldest_key_time = 0);
+    const uint64_t creation_time = 0, const uint64_t oldest_key_time = 0,
+    Env::WriteLifeTimeHint write_hint = Env::WLTH_NOT_SET);
 
 }  // namespace rocksdb

db/column_family.cc

@@ -1015,6 +1015,24 @@ Status ColumnFamilyData::SetOptions(
 }
 #endif  // ROCKSDB_LITE
 
+// REQUIRES: DB mutex held
+Env::WriteLifeTimeHint ColumnFamilyData::CalculateSSTWriteHint(int level) {
+  if (initial_cf_options_.compaction_style != kCompactionStyleLevel) {
+    return Env::WLTH_NOT_SET;
+  }
+  if (level == 0) {
+    return Env::WLTH_MEDIUM;
+  }
+  int base_level = current_->storage_info()->base_level();
+
+  // L1: medium, L2: long, ...
+  if (level - base_level >= 2) {
+    return Env::WLTH_EXTREME;
+  }
+  return static_cast<Env::WriteLifeTimeHint>(level - base_level +
+                            static_cast<int>(Env::WLTH_MEDIUM));
+}
+
 ColumnFamilySet::ColumnFamilySet(const std::string& dbname,
                                  const ImmutableDBOptions* db_options,
                                  const EnvOptions& env_options,

db/column_family.h

@@ -339,6 +339,8 @@ class ColumnFamilyData {
 
   bool initialized() const { return initialized_.load(); }
 
+  Env::WriteLifeTimeHint CalculateSSTWriteHint(int level);
+
  private:
   friend class ColumnFamilySet;
   ColumnFamilyData(uint32_t id, const std::string& name,

db/compaction_job.cc

@@ -297,7 +297,8 @@ CompactionJob::CompactionJob(
       table_cache_(std::move(table_cache)),
       event_logger_(event_logger),
       paranoid_file_checks_(paranoid_file_checks),
-      measure_io_stats_(measure_io_stats) {
+      measure_io_stats_(measure_io_stats),
+      write_hint_(Env::WLTH_NOT_SET) {
   assert(log_buffer_ != nullptr);
   const auto* cfd = compact_->compaction->column_family_data();
   ThreadStatusUtil::SetColumnFamily(cfd, cfd->ioptions()->env,
@@ -368,6 +369,8 @@ void CompactionJob::Prepare() {
   assert(c->column_family_data()->current()->storage_info()
       ->NumLevelFiles(compact_->compaction->level()) > 0);
 
+  write_hint_ = c->column_family_data()->CalculateSSTWriteHint(
+    c->output_level());
   // Is this compaction producing files at the bottommost level?
   bottommost_level_ = c->bottommost_level();
 
@@ -1305,6 +1308,7 @@ Status CompactionJob::OpenCompactionOutputFile(
 
   sub_compact->outputs.push_back(out);
   writable_file->SetIOPriority(Env::IO_LOW);
+  writable_file->SetWriteLifeTimeHint(write_hint_);
   writable_file->SetPreallocationBlockSize(static_cast<size_t>(
       sub_compact->compaction->OutputFilePreallocationSize()));
   sub_compact->outfile.reset(new WritableFileWriter(

db/compaction_job.h

@@ -167,6 +167,7 @@ class CompactionJob {
   std::vector<Slice> boundaries_;
   // Stores the approx size of keys covered in the range of each subcompaction
   std::vector<uint64_t> sizes_;
+  Env::WriteLifeTimeHint write_hint_;
 };
 
 }  // namespace rocksdb

db/db_impl.h

@@ -1316,6 +1316,9 @@ class DBImpl : public DB {
   bool MCOverlap(ManualCompactionState* m, ManualCompactionState* m1);
 
   size_t GetWalPreallocateBlockSize(uint64_t write_buffer_size) const;
+  Env::WriteLifeTimeHint CalculateWALWriteHint() {
+    return Env::WLTH_SHORT;
+  }
 
   // When set, we use a seprate queue for writes that dont write to memtable. In
   // 2PC these are the writes at Prepare phase.

db/db_impl_open.cc

@@ -893,6 +893,7 @@ Status DBImpl::WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
     const uint64_t current_time = static_cast<uint64_t>(_current_time);
 
     {
+      auto write_hint = cfd->CalculateSSTWriteHint(0);
       mutex_.Unlock();
 
       SequenceNumber earliest_write_conflict_snapshot;
@@ -913,7 +914,7 @@ Status DBImpl::WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
           cfd->ioptions()->compression_opts, paranoid_file_checks,
           cfd->internal_stats(), TableFileCreationReason::kRecovery,
           &event_logger_, job_id, Env::IO_HIGH, nullptr /* table_properties */,
-          -1 /* level */, current_time);
+          -1 /* level */, current_time, write_hint);
       LogFlush(immutable_db_options_.info_log);
       ROCKS_LOG_DEBUG(immutable_db_options_.info_log,
                       "[%s] [WriteLevel0TableForRecovery]"
@@ -1007,6 +1008,7 @@ Status DB::Open(const DBOptions& db_options, const std::string& dbname,
     return s;
   }
   impl->mutex_.Lock();
+  auto write_hint = impl->CalculateWALWriteHint();
   // Handles create_if_missing, error_if_exists
   s = impl->Recover(column_families);
   if (s.ok()) {
@@ -1022,6 +1024,7 @@ Status DB::Open(const DBOptions& db_options, const std::string& dbname,
         LogFileName(impl->immutable_db_options_.wal_dir, new_log_number),
         &lfile, opt_env_options);
     if (s.ok()) {
+      lfile->SetWriteLifeTimeHint(write_hint);
       lfile->SetPreallocationBlockSize(
           impl->GetWalPreallocateBlockSize(max_write_buffer_size));
       {

db/db_impl_write.cc

@@ -1168,6 +1168,7 @@ Status DBImpl::SwitchMemtable(ColumnFamilyData* cfd, WriteContext* context) {
       BuildDBOptions(immutable_db_options_, mutable_db_options_);
   const auto preallocate_block_size =
     GetWalPreallocateBlockSize(mutable_cf_options.write_buffer_size);
+  auto write_hint = CalculateWALWriteHint();
   mutex_.Unlock();
   {
     if (creating_new_log) {
@@ -1193,6 +1194,7 @@ Status DBImpl::SwitchMemtable(ColumnFamilyData* cfd, WriteContext* context) {
         // use preallocate_block_size instead
         // of calling GetWalPreallocateBlockSize()
         lfile->SetPreallocationBlockSize(preallocate_block_size);
+        lfile->SetWriteLifeTimeHint(write_hint);
         unique_ptr<WritableFileWriter> file_writer(
             new WritableFileWriter(std::move(lfile), opt_env_opt));
         new_log = new log::Writer(

db/flush_job.cc

@@ -246,6 +246,7 @@ Status FlushJob::WriteLevel0Table() {
   const uint64_t start_micros = db_options_.env->NowMicros();
   Status s;
   {
+    auto write_hint = cfd_->CalculateSSTWriteHint(0);
     db_mutex_->Unlock();
     if (log_buffer_) {
       log_buffer_->FlushBufferToLog();
@@ -315,7 +316,7 @@ Status FlushJob::WriteLevel0Table() {
           mutable_cf_options_.paranoid_file_checks, cfd_->internal_stats(),
           TableFileCreationReason::kFlush, event_logger_, job_context_->job_id,
           Env::IO_HIGH, &table_properties_, 0 /* level */, current_time,
-          oldest_key_time);
+          oldest_key_time, write_hint);
       LogFlush(db_options_.info_log);
     }
     ROCKS_LOG_INFO(db_options_.info_log,

db/repair.cc

@@ -401,6 +401,8 @@ class Repairer {
       status = env_->GetCurrentTime(&_current_time);  // ignore error
       const uint64_t current_time = static_cast<uint64_t>(_current_time);
       SnapshotChecker* snapshot_checker = DisableGCSnapshotChecker::Instance();
+
+      auto write_hint = cfd->CalculateSSTWriteHint(0);
       status = BuildTable(
           dbname_, env_, *cfd->ioptions(), *cfd->GetLatestMutableCFOptions(),
           env_options_, table_cache_, iter.get(),
@@ -411,7 +413,7 @@ class Repairer {
           CompressionOptions(), false, nullptr /* internal_stats */,
           TableFileCreationReason::kRecovery, nullptr /* event_logger */,
           0 /* job_id */, Env::IO_HIGH, nullptr /* table_properties */,
-          -1 /* level */, current_time);
+          -1 /* level */, current_time, write_hint);
       ROCKS_LOG_INFO(db_options_.info_log,
                      "Log #%" PRIu64 ": %d ops saved to Table #%" PRIu64 " %s",
                      log, counter, meta.fd.GetNumber(),

env/io_posix.cc

@@ -35,6 +35,11 @@
 #include "util/string_util.h"
 #include "util/sync_point.h"
 
+#if defined(OS_LINUX) && !defined(F_SET_RW_HINT)
+#define F_LINUX_SPECIFIC_BASE 1024
+#define F_SET_RW_HINT         (F_LINUX_SPECIFIC_BASE + 12)
+#endif
+
 namespace rocksdb {
 
 // A wrapper for fadvise, if the platform doesn't support fadvise,
@@ -858,6 +863,17 @@ bool PosixWritableFile::IsSyncThreadSafe() const { return true; }
 
 uint64_t PosixWritableFile::GetFileSize() { return filesize_; }
 
+void PosixWritableFile::SetWriteLifeTimeHint(Env::WriteLifeTimeHint hint) {
+#ifdef OS_LINUX
+  if (hint == write_hint_) {
+    return;
+  }
+  if (fcntl(fd_, F_SET_RW_HINT, &hint) == 0) {
+    write_hint_ = hint;
+  }
+#endif
+}
+
 Status PosixWritableFile::InvalidateCache(size_t offset, size_t length) {
   if (use_direct_io()) {
     return Status::OK();

env/io_posix.h

@@ -132,6 +132,7 @@ class PosixWritableFile : public WritableFile {
   virtual Status Fsync() override;
   virtual bool IsSyncThreadSafe() const override;
   virtual bool use_direct_io() const override { return use_direct_io_; }
+  virtual void SetWriteLifeTimeHint(Env::WriteLifeTimeHint hint) override;
   virtual uint64_t GetFileSize() override;
   virtual Status InvalidateCache(size_t offset, size_t length) override;
   virtual size_t GetRequiredBufferAlignment() const override {

include/rocksdb/env.h

@@ -152,6 +152,16 @@ class Env {
                                      unique_ptr<RandomAccessFile>* result,
                                      const EnvOptions& options)
                                      = 0;
+  // These values match Linux definition
+  // https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/fcntl.h#n56
+  enum WriteLifeTimeHint {
+    WLTH_NOT_SET = 0, // No hint information set
+    WLTH_NONE,        // No hints about write life time
+    WLTH_SHORT,       // Data written has a short life time
+    WLTH_MEDIUM,      // Data written has a medium life time
+    WLTH_LONG,        // Data written has a long life time
+    WLTH_EXTREME,     // Data written has an extremely long life time
+  };
 
   // Create an object that writes to a new file with the specified
   // name.  Deletes any existing file with the same name and creates a
@@ -573,7 +583,8 @@ class WritableFile {
   WritableFile()
     : last_preallocated_block_(0),
       preallocation_block_size_(0),
-      io_priority_(Env::IO_TOTAL) {
+      io_priority_(Env::IO_TOTAL),
+      write_hint_(Env::WLTH_NOT_SET) {
   }
   virtual ~WritableFile();
 
@@ -650,6 +661,11 @@ class WritableFile {
 
   virtual Env::IOPriority GetIOPriority() { return io_priority_; }
 
+  virtual void SetWriteLifeTimeHint(Env::WriteLifeTimeHint hint) {
+    write_hint_ = hint;
+  }
+
+  virtual Env::WriteLifeTimeHint GetWriteLifeTimeHint() { return write_hint_; }
   /*
    * Get the size of valid data in the file.
    */
@@ -738,6 +754,7 @@ class WritableFile {
   friend class WritableFileMirror;
 
   Env::IOPriority io_priority_;
+  Env::WriteLifeTimeHint write_hint_;
 };
 
 // A file abstraction for random reading and writing.