Optimize message memmoves by predicting next message size#501
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vsoulgard wants to merge 2 commits intoboostorg:developfrom
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Optimize message memmoves by predicting next message size#501vsoulgard wants to merge 2 commits intoboostorg:developfrom
vsoulgard wants to merge 2 commits intoboostorg:developfrom
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Solves #462
Instead of memmove everything on every call to
message_reader::prepare_buffer(), we can use Exponential Moving Average (EMA) formula to predict next message size. If predicted message size fits into buffer, we can avoid memmove.Callgrind screenshots (boost_mysql_bench_one_big_row_boost)
Before:Before:
Total instructions - 1184758337
Memcpy instructions - 1030331155
After:
Total instructions - 154287054 (x7.6 less)
Memcpy instructions - 485896 (x2120 less)
It's almost free EMA implementation with high predictive power.