fork fail (Altos System V)

[Brandon S. Allbery]

In <3864 at altos86.Altos.COM>, jerry at altos86.UUCP claims:
+---------------
| In article <506 at oglvee.UUCP> jr at oglvee.UUCP (Jim Rosenberg) writes:
| >it fail on a request to get only 1 page unless I'm out of swap space?  (Which
| >I'm not.  We're getting these with many many thousand blocks of free swap
| >space -- we have a swap(1) which will show these.)
| 
| >Is there a tunable parameter that will rescue me here?  
| 
| Not really.  You really are running out of swap space.  Even though
| "swap -l" may  show plenty of swap space remaining, it is misleading.
| 
| UNIX allocates swap space for the entire .data and .bss regions whenever
| a process is exec'ed.  Even though swap -l shows plenty of swap space 
| available, most of the swap space is allocated to processes, which, although
| they may not currently be swapped out, still tie up the swap space.
+---------------

Something in your explanation does not match reality.

(a) On a system with 8MB RAM, 25776 blocks swap, 436 blocks reported "in use"
    by /etc/swap -l, I have observed "fork failed" and getcpages messages.
    This seems unlikely by your explanation.

(b) On a system with 8MB RAM and a "standard" swap space (12880 blocks), the
    system shouldn't page at all unless you run programs with more text than
    data/bss.  But they *do* page.

Kindly explain these.

++Brandon
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