re: comments on getting the most out of multi-core machines

[Howard Chu <hyc at highlandsun dot com>]

>     * /From/: Bud Davis <bdavis9659 at sbcglobal dot net>
>     * /Date/: Sat, 11 Nov 2006 16:06:44 -0800 (PST)
>
> it is a rare single file that takes more than 30
> seconds to compile (at least with gcc3 and higher). 
> linking the largest executable takes about 3 minutes.
>
> (sorry to be so long-winded getting to the topic!!)
>
> ordinary case is i change a file and re-link.  takes
> less than 3.5 minutes.  even if gcc was infinitely
> fast, it would still be 3 minutes.
>   

Sounds like you'd be well served by an incremental linker, like AIX 
provides. But that's mostly a topic for a binutils list. The AIX tools 
have some good ideas, worth adopting more widely, like recording the 
sizes of functions in each object file. It basically allows each 
individual function to be treated separately, the way traditional 
linkers treat separate .o files. So individual functions can be replaced 
during a relink, leaving the majority of the object file intact (plus or 
minus relocations that moved along the way). It also somewhat blurs the 
distinction between a fully linked executable file and an intermediate 
relocatable object, since executables can also be incrementally 
relinked. It's a real timesaver when you just need to fix one file in a 
very large program.

--
 -- Howard Chu
 Chief Architect, Symas Corp.  http://www.symas.com
 Director, Highland Sun        http://highlandsun.com/hyc
 OpenLDAP Core Team            http://www.openldap.org/project/