Re:Dense bitpacking
by Someone on Sunday August 09, 2015 @01:33PM
(#10030782)
Of course, it needs benchmarking, but "one int64_t and a boolean" is bad, cache-wise, so I would expect it to slow down the code more than putting those two fields in 5 bits.
Also, I doubt he needed to pack below 64 bits, as the article states "which fits into 61 bits (8 bytes).".
Re:Dense bitpacking
by eloff on Monday August 10, 2015 @09:37AM
(#10034447)
It depends, as always, if you access it sequentially, iterating two separate arrays vs one is similar in performance, the prefetcher will help with both. If it's random access, then you really want things to fit into 64 bits.
Also, I doubt he needed to pack below 64 bits, as the article states "which fits into 61 bits (8 bytes).".