SV: [MapProxy] SV: Response time question

[Johan Sandberg]

Hej!
Yes that's offcourse true. This leads to not so greate performance on bigger image sizes with Map Proxy. 
Measuring directly to the WMS I see that the scaling is only twice the time.
To a certain image size there is no use of using M.P for better perfromance according to the tests I perform.
 
/ Johan
________________________________________
Från: Rahkonen Jukka [Jukka.Rahkonen at mmmtike.fi]
Skickat: den 11 april 2011 11:07
Till: Johan Sandberg
Kopia: mapproxy at lists.osgeo.org
Ämne: Re: [MapProxy] SV: Response time question

Hi,

He means that if you'll take four times more pixels
(800x600=480000 vs 400x300=120000)
then you'll need approximately four times longer time.
Rather logical and to my experience pretty accurate approximation.

-Jukka Rahkonen-



Johan Sandberg wrote:
>
> Hej!
>
> "MapProxy should scale linear with the number of pixels. So
> you should expect 1/4 requests when changing from 400x300 to
> 800x600. You should measure the times with one concurrent
> requests at first and then you should look how you can scale
> that with increased concurrency, see below."
>
> So do you mean that I could expect four times the time to
> fetch an image that comes from seeded tiles when the
> requested image size double?
>
> Is there any good documenations on this? Would be pretty helpful!
>
> / Johan
>
>
> ________________________________________
> Från: Oliver Tonnhofer [olt at omniscale.de]
> Skickat: den 31 mars 2011 17:34
> Till: Johan Sandberg
> Kopia: mapproxy at lists.osgeo.org
> Ämne: Re: Response time question
>
> Hej Johan,
>
> On 31.03.2011, at 15:07, Johan Sandberg wrote:
>
> > hey!
> >
> > I'm measuring responses to Map Proxy when its seeded.
> > I dont get that satisfying response time as a wish. When I
> perform requests of a image size of 400*300, 10 request at
> the time I get low response time(around 50, 60ms).
> >
> > When I do image size of 800*600 the response time is up to 1-2 sec.
> > And even bigger image size give response time up to 5-6 sec.
> > Is this normal response time when requesting seeded tiles?
>
> MapProxy should scale linear with the number of pixels. So
> you should expect 1/4 requests when changing from 400x300 to
> 800x600. You should measure the times with one concurrent
> requests at first and then you should look how you can scale
> that with increased concurrency, see below.
>
> > The request should be alligned with the resolution that is
> seeded so they don't have to re scaled.
> > How much is the normal cost in time of rescaling an image?
> Do the request have to be perfectly alligned with the cached
> resolution to achieve the low response time that I wish?
>
> Depends on the resampling method, you have to check for your
> self. The performance can degrade dramatically when you
> request a lower resolution than your first/upper level,
> because it then needs to merge lots of tiles. So make sure
> you don't run into that.
>
> > I have installed map proxy on a Linux computer with httpd
> apache server. I followed the wgsi example.
>
> You should run mod_wsgi with multiple daemon processes when
> you have more than one CPU:
> http://code.google.com/p/modwsgi/wiki/ConfigurationDirectives
>
> Regards,
> Oliver
>
> --
> Oliver Tonnhofer    | Omniscale GmbH & Co KG    | http://omniscale.de
> http://mapproxy.org | https://bitbucket.org/olt | @oltonn
>
>
>
>
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