From 08be1803eecb5ae464440812ea06e79b21289053 Mon Sep 17 00:00:00 2001 From: Igor Canadi Date: Mon, 13 Apr 2015 15:58:45 -0700 Subject: [PATCH] Fix bad performance in debug mode Summary: See github issue 574: https://github.com/facebook/rocksdb/issues/574 Basically when we're running in DEBUG mode we're calling `usleep(0)` on every mutex lock. I bisected the issue to https://reviews.facebook.net/D36963. Instead of calling sleep(0), this diff just avoids calling SleepForMicroseconds() when delay is not set. Test Plan: bpl=10485760;overlap=10;mcz=2;del=300000000;levels=2;ctrig=10000000; delay=10000000; stop=10000000; wbn=30; mbc=20; mb=1073741824;wbs=268435456; dds=1; sync=0; r=100000; t=1; vs=800; bs=65536; cs=1048576; of=500000; si=1000000; ./db_bench --benchmarks=fillrandom --disable_seek_compaction=1 --mmap_read=0 --statistics=1 --histogram=1 --num=$r --threads=$t --value_size=$vs --block_size=$bs --cache_size=$cs --bloom_bits=10 --cache_numshardbits=4 --open_files=$of --verify_checksum=1 --db=/tmp/rdb10test --sync=$sync --disable_wal=1 --compression_type=snappy --stats_interval=$si --compression_ratio=0.5 --disable_data_sync=$dds --write_buffer_size=$wbs --target_file_size_base=$mb --max_write_buffer_number=$wbn --max_background_compactions=$mbc --level0_file_num_compaction_trigger=$ctrig --level0_slowdown_writes_trigger=$delay --level0_stop_writes_trigger=$stop --num_levels=$levels --delete_obsolete_files_period_micros=$del --min_level_to_compress=$mcz --max_grandparent_overlap_factor=$overlap --stats_per_interval=1 --max_bytes_for_level_base=$bpl --memtablerep=vector --use_existing_db=0 --disable_auto_compactions=1 --source_compaction_factor=10000000 | grep ops Before: fillrandom : 117.525 micros/op 8508 ops/sec; 6.6 MB/s After: fillrandom : 1.283 micros/op 779502 ops/sec; 606.6 MB/s Reviewers: rven, yhchiang, sdong Reviewed By: sdong Subscribers: meyering, dhruba, leveldb Differential Revision: https://reviews.facebook.net/D36963 --- util/thread_status_util_debug.cc | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/util/thread_status_util_debug.cc b/util/thread_status_util_debug.cc index b91bc4ee3..94b19f3d2 100644 --- a/util/thread_status_util_debug.cc +++ b/util/thread_status_util_debug.cc @@ -20,10 +20,11 @@ void ThreadStatusUtil::TEST_SetStateDelay( states_delay[state].store(micro, std::memory_order_relaxed); } -void ThreadStatusUtil::TEST_StateDelay( - const ThreadStatus::StateType state) { - Env::Default()->SleepForMicroseconds( - states_delay[state].load(std::memory_order_relaxed)); +void ThreadStatusUtil::TEST_StateDelay(const ThreadStatus::StateType state) { + auto delay = states_delay[state].load(std::memory_order_relaxed); + if (delay > 0) { + Env::Default()->SleepForMicroseconds(delay); + } } #endif // !NDEBUG