[mapserver-dev] MapScript multithreading performance

[Tamas Szekeres]

Adrian,

You should also inspect how the Priviledged time relates to the User
Time in case of the high number of the threads using the system
monitor tool. I'm not sure whether the time of the thread switch
overhead is correctly displayed in the task manager.

As far as I know that the default thread pool size of an ASP.NET
application is set to 25 that might avoid the overhead of the switches
when the number of the processors is not too large.

Best regards,

Tamas



2008/2/13, adrian kruk <adrian.kruk at gmail.com>:
>
> > It would be useful however to extract proper execution times related
> > to the different operations (like map initialization, drawing etc.).
> Map init takes 30-700ms, mostly 100-200ms
> SetExtent, zoomPoint - very fast <<15ms (so fast that cannot catch)
>
> > What happens is only one thread is executing and do subsequents drawings?
> One processor is in 100% usage
>
> > Is the CPU utilization larger when only a few of the threads (5-6)
> > executed simultaneously?
> Processors was in 100% usage (95% my application + 5% other processes)
>
> These resuslts I get after creating ramdisk and coping all shapefile to new
> drive.
> These are processors usage results for different numbers of threads
>
> Threads number : usage
>
> 1:25
> 2:45-50
> 4:70-95
> 8:70-95
> 16:85-95
> 32:85-95
> 64:85-95
> 128:25-95
> 256:25-80
>
> The last tests was interesting. After creating mapobjects ( usage was 100%),
> usage decrease to 25%, but
>  after some time it started to very slow increasing.
> In my test application at start all mapObjects has big scale value, but
> while running scale value is decreasing.
>
> So I think that it depends on scale value. I have a look at the log file. If
> scale value was big (>10^6) then usage was low.
>  But after minutes when scale values was less (<20000) for most of threads,
> usage incresed to 80%.
>
> So I think that usage depends on number of features and/or labels which are
> rendered. Number of features and/or labels affects drawing time. Long
> drawing times for most of threads affects low usage. Why?
>
> I will check what happened if at the same time scales values will be more
> different. It will be more realistic.
>
> Best regards,
> Adrian
>