Mailscanner and server load

[Philip Parsons]

You should add that even though you only have 48 MB free ram most of it
has been place into the  -/+ buffers/cache Linux does this to make
accessing the ram faster. so really you have 706 mb of memory available
to the system.

If you use free -m it shows it in MB. 

-----Original Message-----
From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK] On
Behalf Of Ugo Bellavance
Sent: Thursday, August 26, 2004 8:27 AM
To: MAILSCANNER at JISCMAIL.AC.UK
Subject: Re: Mailscanner and server load

Dave Filchak wrote:

> I found this thread to be interesting as I have just had to upgrade my

> motherboard and ram because the machine was choking. However, in an 
> effort to determine how well the machine is doing now, I wonder if 
> someone would be so kind as to comment on the output of free and 
> vmstat 2 I have posted below. I was not familiar with these tools so I

> am not sure how to read them so if someone would comment on the 
> perceived performance of my machine based on this output and also a 
> brief explanation of how to interpret this output (what does it all 
> mean ;-)
>
> Free:
>
>              total       used       free     shared    buffers
cached
> Mem:       1014712     966252      48460          0     142552
467144
> -/+ buffers/cache:     356556     658156
> Swap:      1020088     187928     832160

Here you can see that your physical ram is 1 GB, that you've got 48 MB
free, plus 658 MB free in the kernel buffer/cache.

You are using 187 MB of swap

>
> Vmstat 2:
>
>    procs                      memory      swap          io     system
> cpu
>  r  b  w   swpd   free   buff  cache   si   so    bi    bo   in    cs
us sy
> id
>  1  0  0 187924  48384 142620 467112    1    6    23    39   20    10
4  1
> 4
>  0  0  0 187924  48384 142628 467104    0    0     0    32  106   236
0  0
> 100
>  0  0  0 187924  48384 142628 467104    0    0     0     0  105   226
0  0
> 100
>  1  0  0 187924  48376 142644 467096    0    0     0    88  126   259
0  0
> 100

First column: r : how many processes are waiting for cpu time.  You've
got only 1 or 0 idle system or almost.

Second column: b: how many processes are waiting for i/o operation,
you've got almost nothing ther.

Third column: w : (according to the man page) w: The number of processes
swapped out but otherwise runnable.  This field is calculated, but Linux
never desperation swaps.

Then I look at the si and so columns:

si: Amount of memory swapped in from disk (kB/s).
so: Amount of memory swapped to disk (kB/s).

so you're barely swapping.

For the rest, please see the man page, it is clear and complete.

>
> Thanks,
>
> Dave
>
> PS ... Sorry to jump into this conversation but I wanted my question 
> to be in context.

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