Re: [PATCH] Simplify crud() in ident.c

On Dec 3, 2007, at 12:19 PM, Jakub Narebski wrote:

Actually it's faster on modern cpu with deep pipelines. The following is simple test on my macbookpro (repeated 3 times and picked lowest one):

$ time ./crudtest 1000000000 old crud... real 0m0.856s user 0m0.839s sys 0m0.011s $ time ./crudtest 1000000000 simple new crud... real 0m0.431s user 0m0.421s sys 0m0.007s

Note: it's compiled with gcc -O2. -O3 gives the same timing; -O:  
simple crud has the same timing while the old crud is 10x slower; -O0  
(off): the simple code is 50% slower than old crud (note: 10x less  
iterations):

$ time ./crudtest0 100000000 old crud... real 0m0.659s user 0m0.638s sys 0m0.008s $ time ./crudtest0 100000000 simple new crud... real 0m1.175s user 0m1.149s sys 0m0.014s

Since the default CFLAGS in git Makefile has -O2, the simple/new code is faster by default.

__Luke