Fundamental defect of the concept of shared libraries

[Masataka Ohta]

In article <1991May20.175555.13943 at batcomputer.tn.cornell.edu>
	shore at theory.TC.Cornell.EDU (Melinda Shore) writes:

>In the proceedings of the Summer 1990 Usenix Conference (Anaheim) there
>are two papers describing different implementations of shared libraries.
>Both papers present results.  Both papers conclude that for programs not
>dominated by startup costs,

Marc Sabatella's paper gives data, 10% for ineffecient coding of library
and maximum of 10% of start up overhead with reasonably large programs.

Moreover, the measurement was done with 68030, which support various
address modes without much performance degradation (because it is already
slow).

>Donn Seeley's paper is
>particularly relevant,

His paper also make measurement with 68030, utilizing its address modes.

I don't say there result is useless. But they are not applicable to
the todays fastest machines.

>in that he's arguing that it is possible to
>have a shared library implementation that is both simple and fast.

See page 30, line 37-38,

	"The PIC implementation is the heart of this prototype"

Similar thing is written in "Conclusion" section, also.

As I already said, PIC (Position Independent Code) imposes several
restrictions to hardware, which many architectures can't obey.

>You just have to know what you're doing.

You had better read papers you referred.

						Masataka Ohta