SUMMARY: Why processes are swapping on solaris 8

From: Petri Asikainen <>
Date: Wed Jan 12 2005 - 05:20:47 EST
Thanks to all, here's quick summary of messages from
Petri Kallberg , John Leadeham and Joohyun Cha
Given information leads me check postgresql database configuration and 



Petri Asikainen wrote:
> Apache 2.0.52  (prefork) is swapping, every forked new process seems to 
> reserve swapspace, but top and vmstat are showing that theres free 
> memory available. Server is wery slow when it get multiple hits...
 >Can I  use any specific gcc options when compiling apache to avoid 

No. Swapping is controlled by OS. I guess you could lock some of your
pages in memory but I don't really think is going to solve your problem.
(and anyway it would require extensive modifications to application)

> Why os allocating swapspace even there's free memory?
If it is using (as opposed to reserving) swap then
there is another cause. Perhaps postgres is doing
full table scans?

> #vmstat -p
>      memory           page          executable      anonymous filesystem
>    swap  free  re  mf  fr  de  sr  epi  epo  epf  api  apo  apf  fpi
>  5659632 1722640 160 73 21  0   0    8    0    0    0    0    0   85

The first line of vmtstat is a meaningless average since booting.
If it is not the first line, there is no sign of a problem.

> fpo  fpf
> 21   21
> # swap -s
> total: 249432k bytes allocated + 192736k reserved = 442168k used, 
> 5386720k available

Reserving swap space is just a mapping within process's address map not
physical action. (ie. hard disk access)
sunmanagers mailing list
Received on Wed Jan 12 05:16:06 2005

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