[Vala] Performance experiments with Vala, C and D-Bus

[Borja Rodríguez Diliz <borja rd proximasystems net>]

Hi all,

I want to use Vala and Dbus for a project in which I need to exchange 
information between objects about 4 Hz .  The final target is to run the 
software on an embedded device (with a limited CPU / RAM)
I performed some tests and I noticed that using Vala instead of plain C 
requires significantly more CPU requirements.

The test:
 - A dbus server with 200 objects registered. Each object sends the 
following signals:
      signalA: a double value with a frequency of 4 Hz
      signalB: a double value every 2 seconds
- A client subscribed to 'signalA'
- A client subscribed to 'signalB'

I have obtained the following results (% CPU used):

vala-test-1 (code based on https://live.gnome.org/Vala/DBusServerSample )

    13.3% dbus-test-server
    18.0% dbus-test-clientA
    17.3% dbus-test-clientB

vala-test-2 (Server using method emit_signal . Clients using method 
signal_subscribe)

    13.3% dbus-test-server
    15.3% dbus-test-clientA
    1.9  % dbus-test-clientB

Plain C (based on http://www.matthew.ath.cx/misc/dbus):

    2.6% dbus-test-server
    2.8% dbus-test-client newSignalA
    2.6% dbus-test-client newSignalB

Environment: Intel(R) Core(TM)2 Quad  CPU Q8200 @ 2.33GHz / 4GB RAM / 
OpenSuse 11.4 64bits
In vala, using 'signal_subscribe' instead of 'connect' saves lot of CPU. 
Why?

Any point/thought about this would be very appreciated.

Thanks in advance,
Borja

Attachment: vala-dbus-performance-tests.tar.gz
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