dynamic_bloom: replace some divide (remainder) operations with shifts in...
dynamic_bloom: replace some divide (remainder) operations with shifts in locality mode, and other improvements Summary: This patch changes meaning of options.bloom_locality: 0 means disable cache line optimization and any positive number means use CACHE_LINE_SIZE as block size (the previous behavior is the block size will be CACHE_LINE_SIZE*options.bloom_locality). By doing it, the divide operations inside a block can be replaced by a shift. Performance is improved: https://reviews.facebook.net/P471 Also, improve the basic algorithm in two ways: (1) make sure num of blocks is an odd number (2) rotate bytes after every probe in locality mode. Since the divider is 2^n, unless doing it, we are never able to use all the bits. Improvements of false positive: https://reviews.facebook.net/P459 Test Plan: make all check Reviewers: ljin, haobo Reviewed By: haobo Subscribers: dhruba, yhchiang, igor, leveldb Differential Revision: https://reviews.facebook.net/D18843
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