I've worked on several projects that use D-Bus (system daemon, if you care) for commercial embedded consumer electronics. Throughput hasn't really been a problem, but we have tended to use it for control/business-logic messaging, not as a high-throughput data path. --Matt <div class="gmail_quote">On Mon, Mar 2, 2009 at 9:48 AM, Schmottlach, Glenn <<a href="mailto:glenn.schmottlach@harman.com">glenn.schmottlach@harman.com</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> I disabled validation in the D-Bus library by hard-coding mode = DBUS_VALIDATION_MODE_WE_TRUST_THIS_DATA_ABSOLUTELY; in dbus-message.c. From what Havoc has said (at least in the past), this *should* disable the bulk of the validation logic. Likewise, I've turned off API checks and assertions. For my simple test case on the Beagle Board, the above actions save me roughly 2 msec in round-trip time. At 10 msec per call (down from 12 msec), it's still not the number I was looking for. In the embedded world, that's enough to make most developers cringe . . . even more so on a "high-end" embedded processor like the TI OMAP 3530 (500 MHz). Perhaps this overhead isn't even noticed on a multi-core, 2+ GHz Pentium where D-Bus was originally intended to be used (since it is an application bus). I was hoping that with a little tweaking and some consideration for performance improving measures, there might be an opportunity to leverage it more effectively in the embedded space. Certainly, with the rise of connected embedded Linux devices, this could be a huge market that ultimately eclipses the desktop. Perhaps the mailing-list lurkers out there already using D-Bus on an embedded platform could chime in with their experiences, offer any optimization techniques, or provide real-world performance statistics on their platforms. I wonder if I am alone in seeing these rather dismal round-trip access times. <div class="im"> -----Original Message----- From: <a href="mailto:dbus-bounces@lists.freedesktop.org">dbus-bounces@lists.freedesktop.org</a> [mailto:<a href="mailto:dbus-bounces@lists.freedesktop.org">dbus-bounces@lists.freedesktop.org</a>] On Behalf Of Havoc Pennington Sent: Sunday, March 01, 2009 11:39 PM To: Thiago Macieira Cc: <a href="mailto:dbus@lists.freedesktop.org">dbus@lists.freedesktop.org</a> </div><div class="im">Subject: Re: DBus-Daemon Optimizations </div><div><div></div><div class="h5">Hi, On Sun, Mar 1, 2009 at 4:03 PM, Thiago Macieira <<a href="mailto:thiago@kde.org">thiago@kde.org</a>> wrote: > You're correct: the daemon unmarshalls, validates and remarshalls the > messages passing through it. If the incoming message is invalid in any > shape or form, it will disconnect the sender and discard the message. > I'm pretty sure that isn't *quite* true; in particular I'm not sure it's right to say it unmarshals and remarshals. It should be getting a DBusMessage object off the wire and then writing the same DBusMessage object to the recipient. It's true that it does a fair bit of validation in converting the incoming bytes to a DBusMessage, but DBusMessage does store the bytes in marshaled form, so unless something is broken there should not be an unmarshal/remarshal. There is some modification of the message (adding more headers, such as sender) so that could have some cost. One possible optimization is to have the sender client include the sender header to begin with and then the bus would just check it. But, doubtful that's a big win. Bottom line, would need to start with some profiling. Pretty obvious I guess. Best I remember, the validation and marshaling code just isn't that fast. I remember more a constant-factor distributed-bloat problem than a fundamental design problem like extra copies. But, if nobody has profiled lately, for all we know some really bad f-up has been introduced in the last few years accidentally. In the past, there have been things like reparsing /etc/group on every message... you never know until you profile. Havoc _______________________________________________ dbus mailing list <a href="mailto:dbus@lists.freedesktop.org">dbus@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/dbus" target="_blank">http://lists.freedesktop.org/mailman/listinfo/dbus</a> _______________________________________________ dbus mailing list <a href="mailto:dbus@lists.freedesktop.org">dbus@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/dbus" target="_blank">http://lists.freedesktop.org/mailman/listinfo/dbus</a> </div></div></blockquote></div>