On Wed, Sep 3, 2014 at 5:20 PM, Paul Eggert <[email protected]> wrote: > Jim Meyering wrote: >> >> can you give performance deltas on moderate >> or pathologically affected inputs? > > > Maybe something like this: > > diff --horizon-lines=100000000000000000000 gnulib/ChangeLog /tmp/ChangeLog > > where the two files are copies. The bug fix sped up performance about 5x on > my platform, which is Fedora 20 x86-64, AMD Phenom II X4 910e.
Thanks for the details. I tried to reproduce using two copies of gnulib/ChangeLog, but saw identical times for before/after runs. I also tried with two copies of the output of "seq 9999999" on a tmpfs file system, with the same result: no discernible difference. I tried both on an AMD FX(tm)-4100 and an Intel(R) Core(TM) i7-4770S Here are the commands I ran: seq 9999999 > /t/1 && cp /t/2 env time src/diff --horizon-lines=100000000000000000000 /t/[12] Then I took the best of five elapsed times and compared. Here's the minimum time on the faster system, both with and without the patch: $ env time src/diff --horizon-lines=100000000000000000000 /t/[12] 1.94user 0.34system 0:02.29elapsed 99%CPU (0avgtext+0avgdata 1112960maxresident)k 0inputs+0outputs (0major+404031minor)pagefaults 0swaps
