Re [Gllug] Interesting article on the MS monopoly

[Nix]

On Fri, 16 Apr 2004, Tethys stipulated:
> 
> Garry Heaton writes:
> 
>>This is precisely my point. If it can be prelinked, as you say, why on earth
>>isn't it the default with distros which are tyring to impress desktop users?
> 
> In my experience, prelinking makes a very minor difference (less than 5%)
> in speed at best, and seems to serve only to fill up my /var filesystem...

Prelinking's effect scales with the number and (to some extent) the type
of shared libraries in use. Every class in a C++ program has one
relocation per virtual method; hence, large C++ programs often have a
*lot* of relocations, and can have their startup sped up greatly by
prelink.

It won't speed up runtime, except inasmuch as its reduces swapping
fractionally by reducing memory consumption (doing relocation dirties
pages, after all).

The most extreme example is probably OOo; on a non-prelinked system,
more than half its startup time is the dynamic linker thinking about
relocations, and more than 5Mb-worth of pages are marked dirty in the
process. (It doesn't help that OOo uses non-PIC shared libraries by
default!)


prelink doesn't write anything unusual to /var: all it writes (other
than, well, all the executables and shared libraries it rewrites) is
/etc/prelink.cache, which you can delete freely (at the cost of slowing
down incremental prelinking). On my largest box, this file is only 400K.

-- 
`If you believe in strong AI, then death is no longer a mystery,
 but merely a lack of adequate backups.' --- Steven McDougall
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