Re: Help me in setting up MaxClients

[Vikrama Sanjeeva <viki.sanjeeva@xxxxxxxxx>]

Hi Jeff,

    Below is statistics from vmstat while everything is running including httpd:

>> vmstat 2 3
 kthr      memory            page            disk          faults      cpu
 r b w   swap  free  re  mf pi po fr de sr rm s0 s1 s3   in   sy   cs us sy id
 0 0 0 32953272 20946824 11 22 0 3 3  0  0 -0  0  1 -0  872 1041  601  0  0 100
 0 0 0 23225344 11281392 51 104 0 0 0 0  0  0  0  3  0 1024 1767  684  0  0 100
 0 0 0 23224768 11280792 1 4 0  0  0  0  0  0  0  0  0  892 1080  473  0  0 100

So with this, I have: 
Free Swap: 22  GB
Free RAM: 10 GB

Here I am doing a defensive supposition by assuming 5/10 GB of Free RAM "could be" occupied by future applications (if any). So, I am left with 5 GB of Free Memory. Same for Free Swap, assuming I am left with 5 GB Free Swap

Putting values in MaxClient Formula:

MaxClient = (RAM Size - some room for other processes) / Avg
HTTPD Process Size

MaxClient = (32768 - 27648) / 12 = 426 (approx)

  Does it mean, I can set MaxClient value to 426 ? If yes, then:

(i) I have to make sure ServerLimit is also = 426  [As per your presentation for MPM prefork] ?
(ii) Make sure backend server node (tomcat AJP port) can accept 426 concurrent requests ?

Bye,
Viki.

On Mon, Jan 25, 2010 at 10:54 PM, Jeff Trawick <trawick@xxxxxxxxx> wrote:

On Mon, Jan 25, 2010 at 1:26 PM, Vikrama Sanjeeva

<viki.sanjeeva@xxxxxxxxx> wrote:

> Hi All,
>
>    Thanks Jeff for the presentation. Its informative.
>
> Actually, I am trying to calculate what MaxClient I can set. I know my
> server is strong and as Danny and you said, setting 600 will not be a risk.
> I however, will prefer to do some calculation to drive this value. Since I
> am not Solaris command expert, therefore I am having difficulty in doing
> calculation.
>
> My objective is to follow below formula to calculate MaxClient as mentioned
> on Apache site:
> http://httpd.apache.org/docs/2.2/misc/perf-tuning.html
>
> "This procedure for doing this is simple: determine the size of your average
> Apache process, by looking at your process list via a tool such as top, and
> divide this into your total available memory, leaving some room for other
> processes."
>
> As I understand, it says:      (RAM Size / Avg HTTPD Process Size) - some
> room for other proceeses

slight fix to your formula:

Max httpd processes = (RAM Size - some room for other processes) / Avg
HTTPD Process Size

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