043cb62d63
Hello and thank you for RocksDB,
I noticed when using log_write_bench that writes were always 88 bytes:
> strace -e trace=write ./log_write_bench -num_records 2 2>&1 | head -n 2
write(3, "\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371"..., 88) = 88
write(3, "\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371\371"..., 88) = 88
> strace -e trace=write ./log_write_bench -record_size 4096 -num_records 2 2>&1 | head -n 2
write(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 88) = 88
write(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 88) = 88
I think this should be:
<< record.assign('X', FLAGS_record_size);
>> record.assign(FLAGS_record_size, 'X');
So fill and not buffer. Otherwise I always see writes of size 88 (the decimal value for chr "X").
string& assign (const char* s, size_t n);
buffer - Copies the first n characters from the array of characters pointed by s.
string& assign (size_t n, char c);
fill - Replaces the current value by n consecutive copies of character c.
perl -le 'print ord "X"'
88
With the change:
> strace -e trace=write ./log_write_bench -record_size 4096 -num_records 2 2>&1 | head -n 2
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 4096) = 4096
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 4096) = 4096
> strace -e trace=write ./log_write_bench -num_records 2 2>&1 | head -n 2
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 249) = 249
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 249) = 249
Thanks.
01c27be5fb
https://reviews.facebook.net/D16239
83 lines
2.3 KiB
C++
83 lines
2.3 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#ifndef GFLAGS
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#include <cstdio>
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int main() {
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fprintf(stderr, "Please install gflags to run rocksdb tools\n");
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return 1;
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}
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#else
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#include <gflags/gflags.h>
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#include "rocksdb/env.h"
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#include "util/histogram.h"
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#include "util/testharness.h"
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#include "util/testutil.h"
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using GFLAGS::ParseCommandLineFlags;
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using GFLAGS::SetUsageMessage;
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// A simple benchmark to simulate transactional logs
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DEFINE_int32(num_records, 6000, "Number of records.");
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DEFINE_int32(record_size, 249, "Size of each record.");
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DEFINE_int32(record_interval, 10000, "Interval between records (microSec)");
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DEFINE_int32(bytes_per_sync, 0, "bytes_per_sync parameter in EnvOptions");
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DEFINE_bool(enable_sync, false, "sync after each write.");
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namespace rocksdb {
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void RunBenchmark() {
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std::string file_name = test::TmpDir() + "/log_write_benchmark.log";
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Env* env = Env::Default();
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EnvOptions env_options;
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env_options.use_mmap_writes = false;
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env_options.bytes_per_sync = FLAGS_bytes_per_sync;
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unique_ptr<WritableFile> file;
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env->NewWritableFile(file_name, &file, env_options);
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std::string record;
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record.assign(FLAGS_record_size, 'X');
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HistogramImpl hist;
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uint64_t start_time = env->NowMicros();
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for (int i = 0; i < FLAGS_num_records; i++) {
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uint64_t start_nanos = env->NowNanos();
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file->Append(record);
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file->Flush();
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if (FLAGS_enable_sync) {
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file->Sync();
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}
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hist.Add(env->NowNanos() - start_nanos);
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if (i % 1000 == 1) {
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fprintf(stderr, "Wrote %d records...\n", i);
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}
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int time_to_sleep =
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(i + 1) * FLAGS_record_interval - (env->NowMicros() - start_time);
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if (time_to_sleep > 0) {
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env->SleepForMicroseconds(time_to_sleep);
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}
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}
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fprintf(stderr, "Distribution of latency of append+flush: \n%s",
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hist.ToString().c_str());
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}
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} // namespace rocksdb
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int main(int argc, char** argv) {
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SetUsageMessage(std::string("\nUSAGE:\n") + std::string(argv[0]) +
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" [OPTIONS]...");
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ParseCommandLineFlags(&argc, &argv, true);
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rocksdb::RunBenchmark();
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return 0;
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}
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#endif // GFLAGS
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