From: davidsen@ariel.crd.GE.COM (william E Davidsen) Subject: Re: Jumptable Performance (Was: Re: shared libs - can everyone be happy with this?) Date: 19 Aug 1992 12:55:41 GMT
In article <1992Aug18.154149.26416@fys.ruu.nl>, hooft@fys.ruu.nl (Rob Hooft) writes:
| Yes, that is what I expect too, but I didn't expect the usertime to go
| down at all, certainly not by over 0.5 seconds. We're talking a
| program here that runs for 25 hard CPU-seconds! I'll be timing again
| this evening, and might even retry the BYTE-bench this time. Twice,
| that is. I guess I'll be using jump-libs for the rest of my linux-life....
Like most things which seem too good to be true, I'm suspicious. Does
anyone have an explanation why adding size and instructions to every
library call would make the program use less user CPU (or appear to)?
Having used jump tables before I have to be suspicious.
If more instructions and bigger size really improved performance we'd
all leave -O off our compiles, right. Therefore it's an interesting
little puzzle.
--
bill davidsen, GE Corp. R&D Center; Box 8; Schenectady NY 12345
I admit that when I was in school I wrote COBOL. But I didn't compile.