Subject: Re: I can run that OS in *one* megabyte...
To: Jason Thorpe <>
From: Chris G. Demetriou <>
List: port-alpha
Date: 08/04/1998 15:37:39
Jason Thorpe <> writes:
> On Tue, 04 Aug 1998 18:07:28 -0400 
>  nm <> wrote:
>  > This machine has 67108864 bytes of real memory so where did the 16113664
>  > bytes go?
>  > 
>  > I assume that the kernel is using this much memory?
> Some of it is buffer cache (spelled out in kernel messages), some of it
> is overhead of kernel page tables needed to map the various pieces of
> kernel address space.


* some of it is kernel.

* some of it is "other data structures initialized early" by MD code, such as:

	* callouts
	* sysvshm segment descriptors
	* sysv semaphore and message queue data structures
	* the buffer structures themselves (in addition to the pages
	  of memory that back the buffer cache

* some of it is other data structures initialized early by MI code, such as:

	* vm_page structures.

A megabyte here, a megabyte there...  8-)