prometheus/tsdb/encoding
Brian Brazil cf76daed2f Avoid WriteAt for Postings.
Flushing buffers and doing a pwrite per posting is expensive
time wise, so go back to the old way for those. This doubles
our memory usage, but that's still small as it's only
~8 bytes per time series in the index. This is 30-40% faster.

benchmark                                                         old ns/op      new ns/op     delta
BenchmarkCompactionFromHead/labelnames=1,labelvalues=100000-4     1101429174     724362123     -34.23%
BenchmarkCompactionFromHead/labelnames=10,labelvalues=10000-4     1074466374     720977022     -32.90%
BenchmarkCompactionFromHead/labelnames=100,labelvalues=1000-4     1166510282     677702636     -41.90%
BenchmarkCompactionFromHead/labelnames=1000,labelvalues=100-4     1075013071     696855960     -35.18%
BenchmarkCompactionFromHead/labelnames=10000,labelvalues=10-4     1231673790     829328610     -32.67%

benchmark                                                         old allocs     new allocs     delta
BenchmarkCompactionFromHead/labelnames=1,labelvalues=100000-4     832571         731435         -12.15%
BenchmarkCompactionFromHead/labelnames=10,labelvalues=10000-4     894875         793823         -11.29%
BenchmarkCompactionFromHead/labelnames=100,labelvalues=1000-4     912931         811804         -11.08%
BenchmarkCompactionFromHead/labelnames=1000,labelvalues=100-4     933511         832366         -10.83%
BenchmarkCompactionFromHead/labelnames=10000,labelvalues=10-4     1022791        921554         -9.90%

benchmark                                                         old bytes     new bytes     delta
BenchmarkCompactionFromHead/labelnames=1,labelvalues=100000-4     129063496     126472364     -2.01%
BenchmarkCompactionFromHead/labelnames=10,labelvalues=10000-4     124154888     122300764     -1.49%
BenchmarkCompactionFromHead/labelnames=100,labelvalues=1000-4     128790648     126394856     -1.86%
BenchmarkCompactionFromHead/labelnames=1000,labelvalues=100-4     120570696     118946548     -1.35%
BenchmarkCompactionFromHead/labelnames=10000,labelvalues=10-4     138754288     136317432     -1.76%

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>
2019-12-16 15:30:49 +00:00
..
encoding.go