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sstable: Fix write buffer size

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The current 4K write buffer is ridiculously small and forces Urchin to
issue small I/O batches. Increase the buffer size to 64K.

Before:

  Results:
  op rate                   : 27265
  partition rate            : 27265
  row rate                  : 27265
  latency mean              : 1.2
  latency median            : 0.9
  latency 95th percentile   : 2.4
  latency 99th percentile   : 10.6
  latency 99.9th percentile : 14.3
  latency max               : 44.7
  Total operation time      : 00:00:30
  END

After:

  Results:
  op rate                   : 35365
  partition rate            : 35365
  row rate                  : 35365
  latency mean              : 0.9
  latency median            : 0.8
  latency 95th percentile   : 1.8
  latency 99th percentile   : 8.8
  latency 99.9th percentile : 21.8
  latency max               : 272.2
  Total operation time      : 00:00:34
  END

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
This commit is contained in:
Pekka Enberg
2015-06-03 12:35:26 +03:00
committed by Avi Kivity
parent 3d7049f0de
commit 0993142d8d
1 changed files with 4 additions and 2 deletions
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6
sstables/sstables.cc
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@@ -1177,9 +1177,11 @@ future<> sstable::write_components(const memtable& mt) {
_components.insert(component_type::CRC);
}
constexpr size_t sstable_buffer_size = 64*1024;
// TODO: Add compression support by having a specialized output stream.
auto w = make_shared<checksummed_file_writer>(_data_file, 4096, checksum_file);
auto index = make_shared<file_writer>(_index_file, 4096);
auto w = make_shared<checksummed_file_writer>(_data_file, sstable_buffer_size, checksum_file);
auto index = make_shared<file_writer>(_index_file, sstable_buffer_size);
prepare_summary(_summary, mt);
auto filter_fp_chance = mt.schema()->bloom_filter_fp_chance();