[Accessibility] Re: [Accessibility-atspi] D-Bus AT-SPI - The way forward

Mark Doffman mark.doffman at codethink.co.uk
Thu Dec 6 04:15:56 PST 2007

Hi Aaron,

Sorry for repeat, managed to not cc lists last time.

On Wed, 2007-12-05 at 12:30 -0500, Aaron M Leventhal wrote:
> Mark, did you try testing Orbit with a direct connection? 

All of the ORBit calls are direct. To clarify, in the D-Bus case all
connections made are using local unix sockets. In the non-direct case
messages are passed to an intermediate process, the bus-daemon, before
being forwarded on to their destination. 

> This suggestions was from George Kraft: 
> > How are your Orbit2 results impacted if your $HOME/.orbitrc has set 
> > the following?
> > 
> > ORBLocalOnly=1 

I was running without an .orbitrc file, so the standard properties in
the code were used. The standard setup is to use unix sockets
(ORBIIOPUsock=1). Adding the configuration above, and disabling USock
caused worse performance. (Approx 10% slowdown). Simply adding the lines
above without disabling USock didn't make much of a difference. 


> - Aaron 
> Mark Doffman
> <mark.doffman at codethink.co.uk> 
> Sent by:
> accessibility-atspi-bounces at lists.linux-foundation.org 
> 12/05/2007 11:56 AM 
>                To
> accessibility-linux-foundation <accessibility at lists.linux-foundation.org>, accessibility-atspi-linux-foundation <accessibility-atspi at lists.linux-foundation.org>, gnome-accessibility-devel <gnome-accessibility-devel at gnome.org>, kde-accessibility <kde-accessibility at kde.org> 
>                cc
>           Subject
> [Accessibility-atspi] D-Bus AT-SPI - The way forward
> Hello all,
> Available at http://live.gnome.org/GAP/AtSpiDbusInvestigation is the
> results of an investigation into a move of the AT-SPI interface to a
> D-Bus transport. The investigation mainly looks at the relative
> performance of ORBit and D-Bus, but also details some architectural
> issues and a preliminary task list.
> In brief:
> Performance:
> GOK and Orca were profiled to get a good idea of the type of traffic
> on
> the AT-SPI interface. Using this information the performance of some
> of
> the most common method calls were tested in D-Bus and ORBit.
> D-Bus is undoubtedly slower at most of the common method calls, 5-6x
> slower when making a call that passes one int as an argument. When
> passing more data per call this speed difference decreases. ORBit
> takes
> a long time to pass an Object reference, making D-Bus up to 1.5x
> faster
> at these method calls.
> Although D-Bus is the slower transport, looking at the calls made by
> Orca and GOK, we feel it will be possible to provide sensible caching
> that should mitigate this effect.
> Tasks:
> For a switchover to D-Bus a number of core libraries will need to have
> the transport mechanism changed: cspi, pyatspi, GAIL. There will also
> need to be a new Java accessibility back end. Some core D-Bus work is
> also needed, in the areas of interface specification, bindings and
> possibly optimisation.
> If you are interested please go and take a look at the wiki page. We'd
> really like to get every ones opinion on what the way forward for
> is in terms of its transport mechanism.
> Thanks
> Mark
> -- 
> Mark Doffman, Codethink Ltd. - http://codethink.co.uk
> _______________________________________________
> Accessibility-atspi mailing list
> Accessibility-atspi at lists.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/accessibility-atspi
Mark Doffman, Codethink Ltd. - http://codethink.co.uk

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