On Sat, Feb 10, 2024, 03:06 Chet Ramey <chet.ra...@case.edu> wrote: > On 2/3/24 3:29 PM, Casey Johnson wrote: > > > Bash Version: 5.1 > > Patch Level: 16 > > Release Status: release > > > > Description: > > > > The current implementation of the command history takes a long time to > load > > a large HISTFILE when history is stifled. This is because there is a > > memmove() for every line of HISTFILE once HISTSIZE lines have been > loaded. > > If N is the number of lines in HISTFILE then the cost of the memmoves > ends > > up being something like (N - HISTSIZE) * HISTSIZE, peaking when HISTSIZE > is > > roughly N/2. > > Thanks for the report and the patch. I applied it with some tweaks and > saw a dramatic performance improvement for very large history files (I > tested with one that was about 690000 entries) where HISTSIZE is > significantly smaller (I tested with HISTSIZE=100000): from around 11 > seconds to less than 0.3 seconds. >
++ speed optimization greets ++ Chet > > -- > ``The lyf so short, the craft so long to lerne.'' - Chaucer > ``Ars longa, vita brevis'' - Hippocrates > Chet Ramey, UTech, CWRU c...@case.edu http://tiswww.cwru.edu/~chet/ > >
