On Fri, 2007-08-24 at 08:33 +0200, Dirk Eibach wrote: > Hello Philippe, > > tank you for your detailed answer. > > >> Hello, > >> > >> I am trying to understand some performance problems I ran into on my > >> xenomai system. > >> > >> The testcode I attached performs a syscall(gettimeofday). Measuring time > >> on > >> a vanilla Kernel gives the following output: > >> > >> ticks for ppc_getccounter: 116, for gettimeofday: 1479 > >> > >> The same kernel with xenomai patched in gives this: > >> > >> ticks for ppc_getccounter: 116, for gettimeofday: 4278 > >> > >> Is this the expected behaviour? Why is the time for a system call nearly 3 > >> times as much? > >> > > > > When reporting figures, please report all of them. Here is your test ran > > on a 405GPr, linux-2.6.14, I-pipe 1.5-03, with full output: > > > > bash-3.00# ./ppc405_rt > > ticks for ppc_getccounter: 122, for gettimeofday: 7337 > > ticks for ppc_getccounter: 208, for gettimeofday: 2816 > > ticks for ppc_getccounter: 210, for gettimeofday: 2512 > > ticks for ppc_getccounter: 174, for gettimeofday: 2622 > > ticks for ppc_getccounter: 174, for gettimeofday: 2320 > > ticks for ppc_getccounter: 208, for gettimeofday: 2634 > > ticks for ppc_getccounter: 174, for gettimeofday: 2344 > > ticks for ppc_getccounter: 208, for gettimeofday: 2660 > > ticks for ppc_getccounter: 174, for gettimeofday: 2320 > > ticks for ppc_getccounter: 208, for gettimeofday: 2816 > > ticks for ppc_getccounter: 208, for gettimeofday: 2734 > > ticks for ppc_getccounter: 208, for gettimeofday: 2802 > > ... > > I certainly tried to pick a representative sample. Here is the full series > with xenomai patched in: > # ./syscall-test > ticks for ppc_getccounter: 92, for gettimeofday: 18375 > ticks for ppc_getccounter: 116, for gettimeofday: 4250 > ticks for ppc_getccounter: 116, for gettimeofday: 4416 > ticks for ppc_getccounter: 116, for gettimeofday: 4372 > ticks for ppc_getccounter: 116, for gettimeofday: 4486 > ticks for ppc_getccounter: 116, for gettimeofday: 4376 > ticks for ppc_getccounter: 116, for gettimeofday: 4446 > ticks for ppc_getccounter: 116, for gettimeofday: 4434 > ticks for ppc_getccounter: 116, for gettimeofday: 4368 > ticks for ppc_getccounter: 116, for gettimeofday: 4418 > ticks for ppc_getccounter: 116, for gettimeofday: 4404 > ticks for ppc_getccounter: 116, for gettimeofday: 4384 > ... > > > And here we go without: > # ./syscall-test > ticks for ppc_getccounter: 92, for gettimeofday: 6761 > ticks for ppc_getccounter: 116, for gettimeofday: 1768 > ticks for ppc_getccounter: 116, for gettimeofday: 1594
I have comparable values on the 405GPr in the vanilla case: ticks for ppc_getccounter: 127, for gettimeofday: 6851 ticks for ppc_getccounter: 177, for gettimeofday: 1733 ticks for ppc_getccounter: 153, for gettimeofday: 1455 ticks for ppc_getccounter: 153, for gettimeofday: 1401 but still much lower values than you have in the Xenomai case. The answer is either: - in your kernel configuration, - in the I-pipe patch, - in the Xenomai version you are currently using Btw, where does the I-pipe patch 2.6.18 1.5-00 you seem to be using come from? Where did you pick it? > ticks for ppc_getccounter: 116, for gettimeofday: 1560 > ticks for ppc_getccounter: 116, for gettimeofday: 1600 > ticks for ppc_getccounter: 116, for gettimeofday: 1574 > ticks for ppc_getccounter: 116, for gettimeofday: 1618 > ticks for ppc_getccounter: 116, for gettimeofday: 1560 > ticks for ppc_getccounter: 116, for gettimeofday: 1600 > ticks for ppc_getccounter: 116, for gettimeofday: 1540 > ticks for ppc_getccounter: 116, for gettimeofday: 1618 > ticks for ppc_getccounter: 116, for gettimeofday: 1566 > ticks for ppc_getccounter: 116, for gettimeofday: 1608 > ... > -- Philippe. _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
