[comp.unix.aux] Running out of swap space?

ksand@Apple.COM (Kent Sandvik) (01/21/91)

In article <22762@well.sf.ca.us> espen@well.sf.ca.us (Peter Espen) writes:
>
>	I have a 26K block partition on my A/UX 2.0 system. Why
>do I start getting out of swap space errors to the console 
>when a swap -l command shows that I have 13K blocks of  
>free swap space?

The swap space is used all the time, for instace a big process
(X Server or something similar) has to be swapped out, however
there's not enough space for the swap. In most cases one needs
to create more swap space, either on the same or another hard disk
drive. There is no such thing as virtual memory.

Regards,
Kent Sandvik


-- 
Kent Sandvik, Apple Computer Inc, Developer Technical Support
NET:ksand@apple.com, AppleLink: KSAND  DISCLAIMER: Private mumbo-jumbo
Zippy++ says: "Read my lips, no more C++ syntax..."

ksand@Apple.COM (Kent Sandvik) (01/22/91)

In article <1991Jan21.043607.22853@servalan.uucp> rmtodd@servalan.uucp (Richard Todd) writes:
>ksand@Apple.COM (Kent Sandvik) writes:
>>In article <22762@well.sf.ca.us> espen@well.sf.ca.us (Peter Espen) writes:
>
>>>	I have a 26K block partition on my A/UX 2.0 system. Why
>>>do I start getting out of swap space errors to the console 
>>>when a swap -l command shows that I have 13K blocks of  
>>>free swap space?
>
>>The swap space is used all the time, for instace a big process
>>(X Server or something similar) has to be swapped out, however
>>there's not enough space for the swap. In most cases one needs
>>to create more swap space, either on the same or another hard disk
>>drive. There is no such thing as virtual memory.
>
>That's all true, but it doesn't answer the question, namely, why the kernel
>says "WARNING: Swap Space Running Low" when you're *nowhere* *near* having
>the swap space full.  I have two swap partitions, each one 10 Meg.  Current
>total usage by all processes (as best I can tell, from a little VM monitor
>program I wrote), is around 13M.  Given an 8M Mac with about 5.5M free for 
>processes, that means that only about 7.5M of swap space should be in
>use, and indeed as we can see:
>37 servalan /usr/spool/uucp[5:34pm] % swap -l
>path              dev  swaplo blocks   free
>/dev/dsk/c0d0s1  24,1       0  20480  11792
>/dev/dsk/c2d0s1  26,1       0  20480  15216
>Noting that a "block" is 0.5K, this does indeed work out to about 7M of swap
>space in use out of a total of 20M.  So why does the kernel insist on giving
>warnings when less than half of my swap space is actually in use?  
>
>   In answer to the original poster: Ignore the warnings.  Trust me, when you
>really run out of swap space, you'll know it :-).  

Well, I can't answer much to that :-). Only that measuring swap space 
sizes in a multitasking environment is a tricky thing. One moment you
measure it's OK, meanwhile the scheduler is pushing for more space for
a swap. I've seen these messages with big processes running in the system,
and sure more swap space seems to help...

Regards,
Kent Sandvik


-- 
Kent Sandvik, Apple Computer Inc, Developer Technical Support
NET:ksand@apple.com, AppleLink: KSAND  DISCLAIMER: Private mumbo-jumbo
Zippy++ says: "Read my lips, no more C++ syntax..."