From: Petri Asikainen (paca@sci.fi)
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
usage.
Cheers,
Petri
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
swapping?
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)
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