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Re: How to activate swap?

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From Alain Knaff <alain@knaff.lu>
Newsgroups comp.sys.3b1
Subject Re: How to activate swap?
Date Mon, 24 Oct 2022 08:40:20 +0200
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Hi Jesse,

On 24/10/2022 07:45, J Booth wrote:

> Hi Alain.
>
>>> I conclude by this that only about 2.5MB are available in *total*
> So it hit me today, I recall seeing the memory map for the 4MB RAM address space (0x0 - 0x3FFFFF), and sure enough, only around 2.5 MB allocated to user processes:
>
> KERNEL ONLY = 00_00_00 – 07_FF_FF (512 KB)
> User Process = 08_00_00 – 2F_FF_FF (2.5 MB)
> Shared Lib = 30_00_00 – 37_FF_FF (512 KB)

Yes, I have figured this out since then
> Kernel VM = 38_00_00 – 3F_FF_FF (512 KB)

That bit I didn't know yet. As far as I know, Linux does the same (i.e.
the kernel exists in the application's address space, even though
inaccessible to the application, obviously)

>
> So I don't think increasing swap is going to help much given the limited address space.

Actually, the problem that I used to have was running "many" *processes*
concurrently.

When configuring a software package using GNU autoconf, at some point in
time there's a multi-step pipeline and each step implies needs an
additional shell process. With ksh or bash (containing a full load of
config variables), and just 3 or 4 steps of pipeline, this was enough to
run out of VM. Adding more swap resolved the issue. Back then, I did add
more swap "the hard way" by re-installing from floppies and choosing
more swap at the appropriate step. But nowadays, I just use dgesswein's
s4vol tool
Next challenge is to get gcc-3.3.6 (running on UnixPC) to compile a
program longer than a simple hello-world. It runs out of memory pretty
quickly, and as this is one process, swap does not help that use case.

>
>    Jesse
>

Regards,

Alain

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Thread

How to activate swap? Alain Knaff <alain@knaff.lu> - 2022-05-26 19:48 +0000
  Re: How to activate swap? J Booth <166sunny@gmail.com> - 2022-10-23 22:45 -0700
    Re: How to activate swap? Alain Knaff <alain@knaff.lu> - 2022-10-24 08:40 +0200
      Re: How to activate swap? Peter Schmidt <peter@transcend.aero> - 2022-10-24 04:19 -0700
        Re: How to activate swap? J Booth <166sunny@gmail.com> - 2022-10-24 11:06 -0700
          Re: How to activate swap? Alain Knaff <alain@knaff.lu> - 2022-10-24 22:07 +0200
      Re: How to activate swap? J Booth <166sunny@gmail.com> - 2022-10-24 11:27 -0700
        Re: How to activate swap? J Booth <166sunny@gmail.com> - 2022-10-24 12:20 -0700
        Re: How to activate swap? Alain Knaff <alain@knaff.lu> - 2022-10-24 22:47 +0200

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