AIX 3.1 Kernel Size

AIX 3.1 Kernel Size

Post by Dewey Paciaff » Fri, 08 Feb 1991 04:19:25



I've run the 'size' command on /unix, and it responds that my kernel
is 20.5 MB in size. I understand that the kernel pages, but was just curious
to know if this number is actually correct?
--
Dewey Paciaffi           ...!uunet!edi386!eddjp
 
 
 

AIX 3.1 Kernel Size

Post by John F Haugh » Sat, 09 Feb 1991 22:14:31



Quote:>I've run the 'size' command on /unix, and it responds that my kernel
>is 20.5 MB in size. I understand that the kernel pages, but was just curious
>to know if this number is actually correct?

Yes, it is "correct", however, it is a paging kernel and much of that
space is large tables that are unused until you need them.  It doesn't
mean the same thing it does with any other UNIX-derivative.
--
John F. Haugh II                             UUCP: ...!cs.utexas.edu!rpp386!jfh

"I've never written a device driver, but I have written a device driver manual"
                -- Robert Hartman, IDE Corp.

 
 
 

AIX 3.1 Kernel Size

Post by Rick Poleshu » Sun, 10 Feb 1991 23:50:49




>>I've run the 'size' command on /unix, and it responds that my kernel
>>is 20.5 MB in size. I understand that the kernel pages, but was just curious
>>to know if this number is actually correct?

>Yes, it is "correct", however, it is a paging kernel and much of that
>space is large tables that are unused until you need them.  It doesn't
>mean the same thing it does with any other UNIX-derivative.

I am confused. We have a Model 520 with 16Meg of ram. Our size size
command also shows 20.5 Mb of .BSS ( uninitialized data space ). Even
the Unix kernel can't be using 20 megabytes of tables. I assume that
this memory MUST be used for disk cache buffers. Since real memory is
less than the buffer size AIX is paging cache buffers to disk???????
?????????
--
                | Email - !uunet!ulticorp!ultixrs!rick
Rick Poleshuck  | Voice - (201) 887-9222 Ext. 755
                | Mail  - The Ultimate Corporation, East Hanover, NJ 07936
 
 
 

AIX 3.1 Kernel Size

Post by John F Haugh » Tue, 12 Feb 1991 00:34:06




>>Yes, it is "correct", however, it is a paging kernel and much of that
>>space is large tables that are unused until you need them.  It doesn't
>>mean the same thing it does with any other UNIX-derivative.

>I am confused. We have a Model 520 with 16Meg of ram. Our size size
>command also shows 20.5 Mb of .BSS ( uninitialized data space ). Even
>the Unix kernel can't be using 20 megabytes of tables. I assume that
>this memory MUST be used for disk cache buffers. Since real memory is
>less than the buffer size AIX is paging cache buffers to disk?

I understand your confusion - AIX v3 is either the only UNIX-like kernel
that pages or one of very few.

There are various tables, the process table (struct proc) is one of them,
that are declared as having very large sizes.  If you check out the size
of the process table you will see that it is very large - on the order
of 262,144 entries (I forget the exact value).  All of that space is in
the .bss segment.  Since the kernel pages its own text and data pages,
the .bss segment doesn't exist until needed - the same as your user mode
program.  When a process table entry is referenced and the entry does not
exist, the system will catch a kernel mode page fault and allocate a page
to the process table.

Even many parts of the .text and .data segments are pagable.  It is quite
possible for a fairly small amount of the kernel to be "pinned" at any
given time.  So, when I said that the "size" command on the AIX kernel
doesn't mean anything particularly useful, I mean you have to thoroughly
understand how the system allocates it's memory and fully understand that
the size of the system as reported by various utilities is pretty
meaningless.
--
John F. Haugh II                             UUCP: ...!cs.utexas.edu!rpp386!jfh

"I've never written a device driver, but I have written a device driver manual"
                -- Robert Hartman, IDE Corp.

 
 
 

1. changing AIX 3.1 JFS block sizes

I would like to try using filesystems with 8K blocks, but I can't seem
to find anything about this in info explorer.

The file /usr/include/jfs/fsparam.h contains a line that goes:

#define BSIZE           4096    /* size of file system block (bytes) */

suggesting that it is hard-coded, but the the "Tested Mettle" column
of _UNIX Review_ shows performance stats for 512 1K 2K & 8K bytes per
block file systems.

How do you make an 8K filesystem?  Can it be done without having the
source code to JFS?

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3. Increasing File Table Size in AIX 3.1 (RS/6000)

4. permissions with netatalk

5. Problem with telnet or kernel in AIX 3.1

6. linux router question - 3 NIC's

7. perl 4.010 under AIX 3.1 (3003) and AIX 3.1.5

8. Broken source file in v2.4.7 sources

9. Malloc AIX 3.1 vs. AIX 3.2

10. AIX 3.1 restore program on AIX 1.2?

11. Where to get floppy size XFree86 3.1.2D

12. 2 GB file size limitation in Caldera OpenLinux 3.1 using Samba and ftp server

13. XFree 3.1.2D where can I get nice floppy size files?