Swap in minix3

[Juho Hiltunen]

Hi,

running 3.1.9 (#8934, latest revision). It seems the
mkswap command doesn't exist.

man page on the website, specifically
http://www.minix3.org/manpages/man1/mount.1.html
references to mkswap but the file cannot be found. The man
page is outdated anyway, telling me to mount -s for swap
but it doesn't work.

Questions:
1. What is the status of swap space in minix3? I would
like to add swap.
2. Whatever happened to mkswap?

(My first post, started with minix yesterday)

--

Juho Hiltunen
jhil...@ulapland.fi

[Erik van der Kouwe]

Hi,

> man page on the website, specificallyhttp://www.minix3.org/manpages/man1/mount.1.html

> references to mkswap but the file cannot be found. The man
> page is outdated anyway, telling me to mount -s for swap
> but it doesn't work.

The man-pages on the web page are not up to date. I guess this page
was either taken from another system or it may have been taken from
MINIX VMD, an old fork of MINIX 2 that had some features MINIX did not
have. I recommend you use the man-pages included in the MINIX
installation.

> Questions:
> 1. What is the status of swap space in minix3? I would
> like to add swap.

There is no swap in MINIX3. We do have virtual memory nowadays though.
AFAIK there are no current plans to add swap support.

> 2. Whatever happened to mkswap?

It never existed AFAIK, at least in mainline MINIX (it may have
existed in MINIX VMD).

With kind regards,
Erik

[Zubin Mithra]

Hi,

> man page on the website, specificallyhttp://www.minix3.org/manpages/man1/mount.1.html

> references to mkswap but the file cannot be found. The man
> page is outdated anyway, telling me to mount -s for swap
> but it doesn't work.

The man-pages on the web page are not up to date. I guess this page
was either taken from another system or it may have been taken from
MINIX VMD, an old fork of MINIX 2 that had some features MINIX did not
have. I recommend you use the man-pages included in the MINIX
installation.

> Questions:
> 1. What is the status of swap space in minix3? I would
> like to add swap.

There is no swap in MINIX3. We do have virtual memory nowadays though.
AFAIK there are no current plans to add swap support.

Oh, I thought that paging support was not available in Minix3! Could someone tell me the point at which(svn branch number or some kind of identifier) this was implemented?

Thanks,

zm 

[Erik van der Kouwe]

Hi,

> > There is no swap in MINIX3. We do have virtual memory nowadays though.
> > AFAIK there are no current plans to add swap support.
>
> Oh, I thought that paging support was not available in Minix3! Could someone
> tell me the point at which(svn branch number or some kind of identifier)
> this was implemented?

Version 3.1.4 first introduced paging, although it wasn't quite mature
back then and performed very badly. It has been practically usable
since 3.1.5. Allowing blocks of virtual memory to be fragmented in
physical memory is a more recent thing, but I don't recall which
version that was introduced.

With kind regards,
Erik

[Antoine LECA]

Juho Hiltunen wrote:
> running 3.1.9 (#8934, latest revision). It seems the
> mkswap command doesn't exist.

... any more (since about one year).

> 1. What is the status of swap space in minix3?

See Erik's answer.

> I would like to add swap.

What for? It is probably a tough task, either to bring back the old
MINIX code, which was mainly in {mm,pm}/alloc.c, or to design a new
solution which would fit better with VM.

> 2. Whatever happened to mkswap?

Since you asked... here are the details:

The utility stayed present for some time into the source tree (and was
even regularly compiled), even it the only useful thing that can be done
with it is to set up swap space for old systems...
http://gforge.cs.vu.nl/gf/project/minix/scmsvn/?action=browse&path=/trunk/src/commands/simple/mkswap.c&view=log&pathrev=5838
See also the log message for revision 5839:
- remove everything related to swapping to disk

But you did not need it for much longer: the old code for swapping, very
useful on a memory-limited machine but clumsy with today's ones, had
been dropped earlier, when VM came in at revision 3188 (Nov. 2009):
http://gforge.cs.vu.nl/gf/project/minix/scmsvn/?action=browse&path=/&view=rev&root=minix&revision=3188
And the swapping feature is disabled by default (at config.h level)
since revision 2166 (May 2006):
http://gforge.cs.vu.nl/gf/project/minix/scmsvn/?action=browse&path=/trunk/src/include/minix/config.h&r1=2099&r2=2166
And the installation of a swap space is disabled (at setup level) since
revision 747 (August 2005):
http://gforge.cs.vu.nl/gf/project/minix/scmsvn/?action=browse&path=/trunk/src/commands/scripts/setup.sh&r1=745&r2=747

In other words, swap in MINIX3-current is a relic of the past times
which is disappearing progressively (and should now be completely out).

Antoine