dbus moving into kernel?
Marco Trevisan (Treviño)
mail at 3v1n0.net
Fri Sep 24 15:11:55 CEST 2010
Il giorno gio, 16/09/2010 alle 17.23 +0100, Al Johnson ha scritto:
> kdbus is proof-of-concept at the moment, the idea being to reduce the number
> of context switches needed for each dbus message. One synthetic benchmark
> shows a 3x speed increase on the n900 but speedup in real world applications
> seems much more modest.
Some days ago I've tried to port this patch to the Openmoko kernel,
after applying it to the SHR 2.6.32 kernel (patches at ), I got
these results (in average):
Ping dbus-daemon (s) kdbus (s) speedup
500 ping 3.33 2.13 36.2%
5000 ping 32.59 26.09 19.9%
50000 ping 313.56 176.35 43.8%
Adrien Bustany’s ipc-performances tool with 60000 random 10 char
dbus-daemon query (s) kdbus query (s) speedup
102.75 74.71 27.29%
So, the results are quite good, but the code is actually buggy... In
fact when enabling it for the system dbus session (which our FSO-based
phone mostly uses for exchanging data between apps), some applications
doesn't work as expected (Messages, Contacts...), since the kdbus
"socket" actually just supports only dbus requests with few parameters
(< 8kB) and these apps really have greater requests...
By the way, waiting for kdbus upstream fixes (I've already contacted its
author, who is now aware of the bugs I found), I guess that this system
could give us a nice speedup when with many core applications with very
few sources changes.
PS: More informations about my issues have been filled as comments of
of the alban's blog article linked above.
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