Network: Apache: Speeding up your webserver
(last edit: 2001-06-13)
                   
Introduction
Apache and the GENERIC kernel are a bit slow. This is because you will run out of 
available buffers. You can 'fix' this by compiling a new kernel (read below).

NOTE: this is not THE solution to a slow webserver. The prolem can be a slow (IDE) disk, 
not enough memory, etc.

Kernel changes
You'll have to add/change the following kernel options:

       maxusers       32
       options        NMBCLUSTERS=1024

Taken from '/usr/src/sys/i386/conf/LINT':

"# The `maxusers' parameter controls the static sizing of a number of
# internal system tables by a complicated formula defined in param.c."

The 'NMBCLUSTERS' option has no comment in the LINT file. You shouldn't choose a higer
value than 512 for 'maxusers'. This option is already in your kernel, just change the 
value. The max value of 'NMBCLUSTERS' is unkown to me, I currently have it at 10000 
without any problems. You should first try a higher maxusers before adding the 
'NMBCLUSTERS' option to your kernel.

Before the tweak:

  $root@host:/#sysctl -a
 
    ...
    kern.maxproc: 532
    kern.maxfiles: 1064
    ...
    kern.maxfilesperproc: 1064
    ...
    kern.ipc.nmbclusters: 1024
    ...
    kern.ipc.nmbufs: 4096

After the tweak:

  $root@host:/#sysctl -a
 
    ...
    kern.maxproc: 8212
    kern.maxfiles: 16424
    ...
    kern.maxfilesperproc: 16424
    ...
    kern.ipc.nmbclusters: 10000
    ...
    kern.ipc.nmbufs: 40960


Read this document if you don't know how to compile a kernel. 

Testing
One of the programs you can use for testing is '/usr/ports/www/http_load'. Below are some
before and after results (note that this is NOT the max you can get from your machine,
it is not a intensive test, this test depend also highly on the hardware, etc, etc it is
just an illustration).

Before the tweak:

   $root@host:/#http_load -parallel 40 -seconds 2 node
   http://127.0.0.1: No buffer space available
   ...
   http://127.0.0.1: No buffer space available
   http://127.0.0.1: No buffer space available
   936 fetches, 11 max parallel, 1.22616e+06 bytes, in 2.00591 seconds
   1310 mean bytes/connection
   466.622 fetches/sec, 611275 bytes/sec
   0.327848 mean msecs/connect
   5.83531 mean msecs/first-response

After the tweak: 

   $root@host:/#http_load -parallel 40 -seconds 2 node
   1630 fetches, 17 max parallel, 2.1353e+06 bytes, in 2.00011 seconds
   1310 mean bytes/connection
   814.955 fetches/sec, 1.06759e+06 bytes/sec
   0.314662 mean msecs/connect
   6.33601 mean msecs/first-response


So tweak, test, tweak, test until your happy (don't forget to think about your hardware!!)