Re: Upgrade to dual processor machine?

On 13 Nov 2002 at 10:42, Henrik Steffen wrote:
> > Yes. 2*max connection is minimum. Anything additional is always welcome as long
> > as it does not starve the system.
>
> ok, I tried to set shared_buffers to 65535 now. but then restarting postgres
> fails - it says:
>
> IpcMemoryCreate: shmget(key=5432001, size=545333248, 03600) failed: Invalid argument
>
> and a message telling me to either lower the shared_buffers or raise the
> SHMMAX.

Yes. you need to raise SHMMAX. A good feature of recent linux distro. is that
they set SHMMAX to half of physical memory. A very good default IMO..

>  11:06am  up 1 day, 16:46,  1 user,  load average: 1,32, 1,12, 1,22
> 53 processes: 52 sleeping, 1 running, 0 zombie, 0 stopped
> CPU states: 24,5% user, 11,2% system,  0,0% nice,  5,6% idle
> Mem:  1020808K av, 1006156K used,   14652K free,    8520K shrd,   37204K buff
> Swap: 1028112K av,      60K used, 1028052K free                  849776K cached
> I have now changed the SHMMAX settings to 545333248 and changed the
> shared_buffers to 65535 again. now postgres starts up correctly.
>
> the top result changes to:
>
>  11:40am  up 1 day, 17:20,  1 user,  load average: 2,24, 2,51, 2,14
> 57 processes: 55 sleeping, 2 running, 0 zombie, 0 stopped
> CPU states: 24,7% user, 11,3% system,  0,0% nice,  6,2% idle
> Mem:  1020808K av, 1015844K used,    4964K free,  531420K shrd,   24796K buff
> Swap: 1028112K av,      60K used, 1028052K free                  338376K cached
> now, does this look better in your eyes?

Well, don't look at top to find out free memoy. Use free. On my machine..

[shridhar@perth shridhar]$ free
             total       used       free     shared    buffers     cached
Mem:        255828     250676       5152          0      66564      29604
-/+ buffers/cache:     154508     101320
Swap:       401616      12764     388852
[shridhar@perth shridhar]$

Here the important value is second value in second line, 101320. That's true
free memory. Remeber when system needs memory, it can always shrunk
cache/buffers. In both of your stats, cache+memory are roughly 400MB.

Relax, your system is not starving for memory...

> do you need more information here?

Not for this problem, but just curious. What does uname -a says?

Secondly just curious, with 5000 requests per minute, what is the peak number
of connection you are getting? You should look int pooling parameters for
better performance..

HTH


Bye
 Shridhar

--
Hawkeye's Conclusion:    It's not easy to play the clown when you've got to run
the whole    circus.