Re: [svg-developers] How to time some SVG+JavaScript?
On Tue, 08 Feb 2011 20:57:03 +0100, gb_n_svg gbulme...@yahoo.co.uk wrote:
I have been experimenting with SVG Filters across Safari, Firefox,
Chrome and Opera.
I am trying to get some stable performance timing so that I can
understand which filters are pretty quick, and which aren't. (I'd also
like to do these as browsers are improved)
One general rule of thumb for filters: the larger the area you filter is
the heavier it will be to compute.
Certain filters are faster than others, most depend heavily on what the
attribute values are (e.g for feConvolveMatrix a larger matrix means more
calculations per pixel).
These filters are usually heavier than the others:
- feGaussianBlur (if the area to blur is large and/or 'stdDeviation' is
large. This primitive is one of the ones that is most likely optimized in
browsers, for the normal cases at least.)
- feDisplacementMap
- feTurbulence (if 'numOctaves' is large)
- feConvolveMatrix (if 'order' is large)
- the lighting filters
There are a couple of obstacles:
1. Some stuff is so quick, it can't be reliable measured
2. Some browsers schedule drawing differently, so aren't actually timed
My approach to solve 1 (to make stuff easy to measure) is to run a
JavaScript function to create hundreds of instances of a group, with the
filter applied to each of the groups. This seems to be enough that
timing is relatively useful.
e.g.
function () {
var startTime = new Date();
... do the create and rendering for hundreds of groups ...
var endTime = new Date();
... calculate elapsed time and print it ...
}
The rendering isn't necessarily synchronous, and most likely won't happen
in the midst of running a function like this. A repaint is commonly
requested on completing a javascript thread, essentially what happens
when the function called from the timer returns.
If you add a timer and call some function regularly then you can get a
rough idea of the framerate, but note that implementations that skip
rendering frames would be favored by that. Some implementations may
throttle the framerate to get less jerky animations, or limit the rate of
updates to avoid using too much resources.
For Opera, we added SVGSVGElement.currentFps, which returns a floating
point number representing the current framerate. It should be more
accurate than going by the timer method. We also added
SVGSVGElement.targetFps, which you can use to set the target framerate for
SMIL animations, set it high to strive for a higher framerate, set it low
to conserve resources. An example of how that can be used:
http://dev.opera.com/articles/view/presto-2-2-and-opera-10-a-first-look/#fps.
Note that the example there changes the text in the svg once every 100ms
so the lowest framerate that will be reported is going to be around 10
(100ms timer = 10 updates per second).
Hope this helps
/Erik
--
Erik Dahlstrom, Core Technology Developer, Opera Software
Co-Chair, W3C SVG Working Group
Personal blog: http://my.opera.com/macdev_ed
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[svg-developers] How to time some SVG+JavaScript?
I have been experimenting with SVG Filters across Safari, Firefox, Chrome and
Opera.
I am trying to get some stable performance timing so that I can understand
which filters are pretty quick, and which aren't. (I'd also like to do these as
browsers are improved)
There are a couple of obstacles:
1. Some stuff is so quick, it can't be reliable measured
2. Some browsers schedule drawing differently, so aren't actually timed
My approach to solve 1 (to make stuff easy to measure) is to run a JavaScript
function to create hundreds of instances of a group, with the filter applied to
each of the groups. This seems to be enough that timing is relatively useful.
e.g.
function () {
var startTime = new Date();
... do the create and rendering for hundreds of groups ...
var endTime = new Date();
... calculate elapsed time and print it ...
}
BUT I can't simply time the JavaScript function this way because the rendering
of the graphics doesn't happen until after the function has exited.
I tried running the final part of the timing after the groups are created as a
closure with setTimeout:
setTimeout(function () {
var endTime = new Date();
var diffTime = endTime.getTime() - startTime.getTime();
var txt = document.getElementById(timing);
txt.firstChild.nodeValue = ... ;
}, 10);
But, with some browsers I can see that the time to render is much longer than
the time this code measures and reports (over 2 seconds, but the timing claims
0.6sec)
I'd like to get this to a stage where I can run a sequence of tests,
automatically, let it gather the stats, and compare different combinations of
filters on the same browser, and also between different browsers.
Could someone please point me at something which explains how to time this sort
of thing so that the time includes all of the rendering?
TIA - GB
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Re: [svg-developers] How to time some SVG+JavaScript?
Here's an approach I used in a paper for the SVG2007:
http://srufaculty.sru.edu/david.dailey/svg/SVGOpen2007/SVGOpen2007.htm
I was interested, among other things, in how JavaScript and SMIL animations
interacted, and in the effect of overstuffing the SVG DOM with lots of content.
cheers
David
- Original Message -
From: gb_n_svg
To: svg-developers@yahoogroups.com
Sent: Tuesday, February 08, 2011 2:57 PM
Subject: [svg-developers] How to time some SVG+JavaScript?
I have been experimenting with SVG Filters across Safari, Firefox, Chrome and
Opera.
I am trying to get some stable performance timing so that I can understand
which filters are pretty quick, and which aren't. (I'd also like to do these as
browsers are improved)
There are a couple of obstacles:
1. Some stuff is so quick, it can't be reliable measured
2. Some browsers schedule drawing differently, so aren't actually timed
My approach to solve 1 (to make stuff easy to measure) is to run a JavaScript
function to create hundreds of instances of a group, with the filter applied to
each of the groups. This seems to be enough that timing is relatively useful.
e.g.
function () {
var startTime = new Date();
... do the create and rendering for hundreds of groups ...
var endTime = new Date();
... calculate elapsed time and print it ...
}
BUT I can't simply time the JavaScript function this way because the
rendering of the graphics doesn't happen until after the function has exited.
I tried running the final part of the timing after the groups are created as
a closure with setTimeout:
setTimeout(function () {
var endTime = new Date();
var diffTime = endTime.getTime() - startTime.getTime();
var txt = document.getElementById(timing);
txt.firstChild.nodeValue = ... ;
}, 10);
But, with some browsers I can see that the time to render is much longer than
the time this code measures and reports (over 2 seconds, but the timing claims
0.6sec)
I'd like to get this to a stage where I can run a sequence of tests,
automatically, let it gather the stats, and compare different combinations of
filters on the same browser, and also between different browsers.
Could someone please point me at something which explains how to time this
sort of thing so that the time includes all of the rendering?
TIA - GB
[Non-text portions of this message have been removed]
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