Change default options.delayed_write_rate

Summary: We now have a mechanism to further slowdown writes. Double default options.delayed_write_rate to try to keep the default behavior closer to it used to be.

Test Plan: Run all tests.

Reviewers: IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: yhchiang, kradhakrishnan, rven, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D52281

HISTORY.md

@@ -7,6 +7,7 @@
 * If options.max_write_buffer_number > 3, writes will be slowed down when writing to the last write buffer to delay a full stop.
 * Introduce CompactionJobInfo::compaction_reason, this field include the reason to trigger the compaction.
 * After slow down is triggered, if estimated pending compaction bytes keep increasing, slowdown more.
+* Increase default options.delayed_write_rate to 2MB/s.
 
 ## 4.3.0 (12/8/2015)
 ### New Features

db/db_bench.cc

@@ -642,7 +642,7 @@ DEFINE_uint64(soft_pending_compaction_bytes_limit, 64ull * 1024 * 1024 * 1024,
 DEFINE_uint64(hard_pending_compaction_bytes_limit, 128ull * 1024 * 1024 * 1024,
               "Stop writes if pending compaction bytes exceed this number");
 
-DEFINE_uint64(delayed_write_rate, 2097152u,
+DEFINE_uint64(delayed_write_rate, 8388608u,
               "Limited bytes allowed to DB when soft_rate_limit or "
               "level0_slowdown_writes_trigger triggers");
 

include/rocksdb/options.h

@@ -1170,7 +1170,7 @@ struct DBOptions {
   // gets behind further.
   // Unit: byte per second.
   //
-  // Default: 1MB/s
+  // Default: 2MB/s
   uint64_t delayed_write_rate;
 
   // If true, then DB::Open() will not update the statistics used to optimize

util/options.cc

@@ -261,7 +261,7 @@ DBOptions::DBOptions()
       wal_bytes_per_sync(0),
       listeners(),
       enable_thread_tracking(false),
-      delayed_write_rate(1024U * 1024U),
+      delayed_write_rate(2 * 1024U * 1024U),
       skip_stats_update_on_db_open(false),
       wal_recovery_mode(WALRecoveryMode::kTolerateCorruptedTailRecords),
       row_cache(nullptr),