Re: Enable accessibility by default in development releases?

["Padraig O'Briain" <Padraig Obriain Sun COM>]

It looks to me that display_timeout is called 50 times a second; this
function calls vte_terminal_process_incoming which emits "text-inserted"
signal which causes the accessibility layer to refetch the contents of
the terminal.

I do not expect Kjartan's patch to fix the problem but I would like to
see what difference, if any, it makes.

It looks like we need to be more clever in processing the
"text-inserted" events.

Padraig

On Tue, 2005-11-22 at 21:38 +0000, John Rice wrote:
> Looking at Ross's suggestion and your profile data Padraig, does look
> as if something like the "scrollbar-updated signal is causing the a11y
> layer to refetch the contents of the terminal several times on every
> output"
> 
> So Kjartan's patch replaces the following g_return_if_fail macros in
> vteaccess.c with g_asserts allowing them to be compiled out which is
> great, but I fear the % of cpu time in the function they take up will
> be small relative to the  time taken to update the snap_shot
> text :( But certainly worth trying. Suspect we'll get most mileage out
> of looking how to batch the scroll events, be clever on the type of
> redraw we are doing ...
> 
> JR
> 
> /vte-0.11.15/src/vteaccess.c
>     249 static void
>     250 vte_terminal_accessible_update_private_data_if_needed(AtkObject *text,
>     251 						      char **old, glong *olen)
>     252 {
> 
> 		:
>     259 
>     260 	g_return_if_fail(VTE_IS_TERMINAL_ACCESSIBLE(text));
>     261 
>     262 	/* Retrieve the private data structure.  It must already exist. */
>     263 	priv = g_object_get_data(G_OBJECT(text),
>     264 				 VTE_TERMINAL_ACCESSIBLE_PRIVATE_DATA);
>     265 	g_return_if_fail(priv != NULL);
>     266 
>     267 	/* If nothing's changed, just return immediately. */
>     268 	if ((priv->snapshot_contents_invalid == FALSE) &&
>     269 	    (priv->snapshot_caret_invalid == FALSE)) {
>     270 		if (old) {
>     271 			if (priv->snapshot_text) {
>     272 				*old = g_malloc(priv->snapshot_text->len + 1);
>     273 				memcpy(*old,
>     274 				       priv->snapshot_text->str,
>     275 				       priv->snapshot_text->len);
> 
> 
> 
> 
> Padraig O'Briain wrote: 
> > I have looked at profile data when accessibility is enabled and most of
> > the time is spent in
> > vte_terminal_accessible_update_private_data_if_needed.
> > 
> > I need to apply the patch to replace g_return_if_fail calls with
> > g_assert calls and see what improvement that makes.
> > 
> > Padraig
> > 
> > On Tue, 2005-11-22 at 12:16 +0000, John Rice wrote:
> >   
> > > As can sometimes be the case with automated benchmarks, not quite what
> > > it seems :(
> > > 
> > > Derek had an issue with doing one of the automated benchmarks in
> > > gnome-terminal and gedit, so he went back and rechecked them all
> > > manually. Difference from previous automated results below, when
> > > cat'ing a large file in GT or opening a large file in GEdit.
> > > 
> > > Looks like if you need to cat large files flick the off button :)
> > > Apart from that things look ok for enabling this by default. All the
> > > previous automated benchmark tests were uneffected.
> > > 
> > > JR
> > > Revised results from manually measuring;
> > > 
> > > o cat a big file in gnome-terminal (Using a .html file, 26,332,850 bytes)
> > > -  AllY Off: 40 secs
> > > -  AllY On: 214 secs  (over 500% increase in mean scroll time)
> > > 
> > > o open a file in gedit (same .html file as above)
> > > -  AllY Off: 3.18 sec
> > > -  AllY On:  4.49 sec  (40% increase in mean file load time)
> > > 
> > > 
> > > 
> > > Federico Mena Quintero wrote: 
> > >     
> > > > On Mon, 2005-11-21 at 16:34 +0000, John Rice wrote:
> > > > 
> > > >   
> > > >       
> > > > > Doing 'cat' of a big file in gnome-terminal was the only area where a
> > > > > significant difference was seen. Approx 45 secs with A11Y ON, and 42.4
> > > > > secs with A11Y Off.
> > > > > 
> > > > > All other areas looked at above were not significantly different
> > > > > comparing A11Y On Vs A11Y Off.
> > > > >     
> > > > >         
> > > > This is great news :)  And the difference in gnome-terminal could be
> > > > just noise.
> > > > 
> > > > So, have people *felt* a performance impact from running their session
> > > > with a11y enabled, or is it just a placebo?
> > > > 
> > > > Anyway, let's go ahead with the change - this will let us test the code
> > > > better.
> > > > 
> > > >   Federico
> > > > 
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> > 
> >   
> 
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