It's hard to give a definite answer without seeing your actual setup,
mapfile, data, etc.
However, as a general rule, you will gain from using fastcgi only once
you get to the point where the processing time for each request (to read
data and render the map) becomes close to or smaller than the time it
takes to launch CGI processes. So if you get around 5 hits/sec with 8
cores, we can presume that each request takes over 1 second of
processing time (and/or disk I/O) which is several times larger than the
time to launch a CGI process, and you need to do some work on your data
and mapfile before you can benefit from fastcgi.
Of course I could be completely wrong, but I'd suggest you start by
verifying where the time is spent by enabling MS_ERRORFILE/DEBUG at both
the mapfile and layer level, look at the logs to identify where the time
is spent and optimize your mapfile/data accordingly.
HTH
Daniel
Rahkonen Jukka wrote:
I made some tests by letting JMeter run a few thousand WMS GetMap
requests with varying BBOX and WIDTH and HEIGHT parameter. I tested
three alternatives:
MS4W 2.2.8 and Mapserver 5.2.1
MS4W 3.0 beta 7 and Mapserver 5.6.0 as cgi
MS4W 3.0 beta 7 and Mapserver 5.6.0 a fcgi
Server is Windows 2003 server with 8 cores and fast disks. I configured
JMeter to use 20 threads
I feel I was able to get fcgi running by following the instructiuons of
MS4W README_INSTALL document. I believe it is convinced by a)
calls addressed to /fcgi-bin/mapserv.exe work and b) after receiving an
image from WMS service the process remains on the server for some time.
However, all these three alternatives are giving me about the same
speed that is 5 images per second or 500 KB/sec with jpeg output.
Bandwidth is not the limiting factor because with 24-bit png output I
get a throughput of 4400 KB/sec. It looks like I am having some base
load in my system that takes about 150 milliseconds per each successful
WMS request and using fcgi does not help in my case.
Can anybody suggest why my server is so much slower than the one used in
Mapserver/Geoserver shootout
http://www.slideshare.net/gatewaygeomatics.com/wms-performance-shootout and
why I do not get any advantage from using Fast-CGI? Could it be because
my tileindex shapefile is rather large with more than 11000 polygons?
Images themselves are processed in a standard Mapserver way and they
are uncompressed, tiled geotiffs with external uncompressed overviews.
Some evidence about tileindex handling eating time is that I can get
double speed with 10 images per second from a single ecw file but this
test is not very comparable because my ecw file is black and white and
not 3-channel as my geotiff layer.
-Jukka Rahkonen-
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Daniel Morissette
http://www.mapgears.com/
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