A couple garbage collector questions

[Hannah Schroeter]

Hello!

In article <slrn9d6n13.vlg.kc5tja at garnet.armored.net>,
Samuel A. Falvo II <kc5tja at armored.net> wrote:
>On 10 Apr 2001 16:08:24 +0200, Hannah Schroeter wrote:
>[...]

>>Segmentation is coarse grained and cannot be used to alleviate fine-grained
>>double indirections.

>Why not?  Simply telling me that "it's not possible" isn't enough.  I,
>however, have an overwhelming amount of evidence that it *can* be used for
>this very purpose, especially since Intel segments can be byte-sized
>granular for objects less than 1MB in size.  In addition, the PC/GEOS
>operating system used segmentation to a capacity very close to this.  Should
>I send them an e-mail telling them to please stop, as it's clearly not
>possible?

You *can* use segments of small size, however not too many, IIRC.
As, IIRC, the x86 segment selector registers are of a size of 16 bits,
of which 3 bits are reserved (2 bits mark the privilege level, 1
bit marks whether the segment is in the LDT or the GDT).
Usually the OS grabs the GDT for itself, so you have just the use
of 2^13 LDT segments. If you want to be able to move around single objects
without adjusting pointers, you are limited to max. 2^13 living objects.

Kind regards,

Hannah.