From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds)
Newsgroups: comp.os.linux
Subject: 0.97 patchlevel 3 available
Date: 5 Sep 92 18:46:06 GMT
Organization: University of Helsinki

[ This was already sent to the NORMAL mailing-list, and this is
  essentially the same announcement. ]

Well, 0.97.pl3 is available both as full source (linux-0.97.3.tar.Z) and
as a context diff (linux-0.97.patch3.Z) on nic.funet.fi, in the normal
directory (pob/OS/Linux/testing/Linus).  It seems some line is once more
down on the way to the US, so I haven't uploaded it to tsx-11 yet. 
Also, I haven't been able to use the pub/Linux/Linus directory on
sunsite (it dies on me when I try to send the group password), so I
don't know when sunsite will get the new release. 

Patch3 is almost 100kB even compressed, as there were quite big changes
in the mm and minix fs.  No major new features: there are two new system
calls: swapoff(const char * swapfile) and wait4(), and linux accepts
several swap-files, but the rest of the thing is mostly bug-fixes or
simply rewrites. 

Major changes:
 - new swap-page handling: linux no longer uses just one bit to keep
   track of used swap-space, but a counter for each swap-page.  This
   allows processes to share swap-pages after a fork(), and should
   result in /major/ performance increases on machines with less memory. 
   I've seen better performance even with 8MB - I wouldn't be surprised
   if 4MB machines would re-compile the kernel noticeably faster under
   pl3.  I'd be interested to hear numbers. 
 - The low 1MB memory that isn't used directly by the kernel is now
   swappable memory, instead of being hardcoded for buffer cache.  The
   patches for this were originally by tytso, and I expanded on it a bit
   more.  This might also help better performance on 2-4MB machines. 
   Note that this does /not/ mean that you can use 1M machines for
   linux: linux still needs some extended memory. 
 - the dosfs has been upgraded to dosfs.8 - patches by almesber.
 - I edited the minix fs pretty heavily to remove a couple of race-
   conditions.  The same races still exist in the extended fs, as I
   didn't have time to edit that yet.  The minix-fs took precedence as I
   know that better, and extfs isn't "official" yet anyway. 

other changes:

 - the mouse-driver now handles both Logitech (minor = 0) and PS/2
   (minor = 1) busmice.
 - there is a proc-fs for access to user memory/files etc.
 - better support for the tcp/ip patches (but see below...)
 - corrected symlink and /dev/[k]mem behaviour
 - Lars Wirzenius' README (with minimal comments by me) and the GNU
   COPYING notice are now part of the normal kernel setup, and can be
   found in the tar-archive.
 - the floppy ioctl() to get the FD parameters no longer requires root
   priviledges.  Thus, the msdos emulator runs even for a normal user. 

Some comments on patchlevel 3:

	mm:

The swap-page handling resulted in a reduction of swap-file (or
partition) size to a maximum of 16MB per file.  It's nothing inherent to
the code, but it eased some algorithms, so I didn't bother coding around
it.  After all, 16MB is enough for most people, and if you want more,
you can have up to 128 swapfiles of 16MB each.  If I get enough
hate-mail about it, I might just try to find the energy to correct it. 
Maybe. 

Bigger swapfiles will still work, but linux will take advantage of only
the low 16MB.  Also, there is no nifty logic to try to optimize the
usage of the swap-files: pages are simply allocated from one swap-file
until it fills up, and then the next swap-file is used. 

The memory management changes break ps/free once more, but not very
much.  Also, I changed the load-average counting, so 'w' also needs
slight editing.  On the other hand, I made '/dev/kmem' mmap()able, and
'ps' and 'free' should be edited to take advantage of that: it should
result in much faster operation, as well as possibly using less real
memory. 

	fs:

The fs changes should remove at least two races - the races don't happen
very often, but they were theoretically possible, and might be the
reason for some fs corruption problems that have been reported.  The
changes are related to the use of bmap() - the bmap interface doesn't
really lend itself to some things that it was used for.  Re-writing
internal fs-functions not to use bmap not only should have removed any
races, but also actually resulted in cleaner code. 

The proc-fs code isn't too beautiful, and I'll probably leave it out
from 0.98 unless I can make it loadable.  We'll see.  If anybody wants
to use it, you can do something like

  # mount -t proc /dev/ram /proc

Instead of /dev/ram you can use any block device - it's not used, and is
only a dummy as the proc-fs doesn't actually use any external device. 
(but note that the device is still marked as mounted, so you cannot
mount it for anything else). 

	kernel/mm/lib:

The TCP/IP patches are also essentially in 0.97.pl3 - not the full
TCP/IP directory, only the patches to the main kernel.  NOTE!! I don't
like the 'grab_malloc_pages()' function, so I left that out, and added a
GFP_ATOMIC priority to get_free_page() that should be used instead.  I
hope this will be used (Ross?), as it's a lot cleaner. 

Also, I hope the tcp/ip people will clean up malloc() so that it doesn't
panic instead of returning NULL etc.  Ugly, ugly.  This is related to
the get_free_page(GFP_ATOMIC) changes, and I'd like to have patches as
soon as possible - tcp/ip won't be part of the standard kernel until
that can be cleaned up. 

		Linus