rocksdb/util/thread_status_util_debug.cc
Igor Canadi 82e5c842b6 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
2015-04-13 15:59:29 -07:00

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// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#include <atomic>
#include "rocksdb/env.h"
#include "util/thread_status_updater.h"
#include "util/thread_status_util.h"
namespace rocksdb {
#ifndef NDEBUG
// the delay for debugging purpose.
static std::atomic<int> states_delay[ThreadStatus::NUM_STATE_TYPES];
void ThreadStatusUtil::TEST_SetStateDelay(
const ThreadStatus::StateType state, int micro) {
states_delay[state].store(micro, 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
} // namespace rocksdb