Perrine, what version of the I-pipe patch are you using ?
I use adeos-ipipe-2.6.19-arm-1.6-04.patch. On 6/7/07, Philippe Gerum <[EMAIL PROTECTED]> wrote:
On Thu, 2007-06-07 at 12:07 +0200, Philippe Gerum wrote: > On Thu, 2007-06-07 at 11:25 +0200, Gilles Chanteperdrix wrote: > > Jan Kiszka wrote: > > > Perrine Martignoni wrote: > > > > > >>Ok. I'll do this. > > >> > > >>But I don't understand why the same application compiled without any links > > >>with Xenomai give different results if there is Xenomai in the kernel. > > > > > > > > > [Looking at your numbers again] Hmm, maybe some rounding issue of ticks > > > due to whatever side-effect of I-pipe. We would first of all need the > > > usual set of information (.config, involved versions) and also > > > /sys/devices/system/clocksource/clocksource0/current_clocksource. > > > > Maybe what Perrine is observing is simply the overhead of the I-pipe ? > > I mean, Linux is Xenomai idle task, so it is acceptable for Linux > > numbers to be a bit worse than when Xenomai is not running. > > > > Most of the "known" overhead has disappeared with the PF_EVNOTIFY > extension, so that we relay Linux-originated events (e.g. syscalls) only > to subscribed domains (e.g. Xenomai). ... to subscribed tasks from suscribed domains, more precisely. In effect, Xenomai does not filter syscalls issued from plain Linux tasks anymore. > In the test case we are discussing > of, no relay should be done since no domain did subscribe to receive > those events. > > The best way to check if the I-pipe still adds a noticeable overhead is > to compare: > > - a vanilla kernel running cyclic test, > with > - an I-pipe patched kernel, without Xenomai, using the same .config than > the vanilla kernel used. Without Xenomai either means to not run the > prepare-kernel.sh script, but only patch the kernel with the I-pipe > support, or disable CONFIG_XENOMAI entirely if the preparation script > has been run on the target kernel tree. > > _Having both kernel setups share the very same kernel configuration is > mandatory, otherwise you would end up comparing apples and oranges._ > The best way to make sure of this is to copy the .config file used for > the vanilla kernel to the I-pipe patched one, and run "make oldconfig". > You should be prompted only once, for the new CONFIG_IPIPE switch. Any > other behaviour would be the sign of some discrepancy in your test > configuration. > > Since we can't have any temporal predictability for such configs, the > max value the cyclic test reports has no meaning. The useful figures are > the min and average values, as observed for a few minutes while the > board/box is sitting doing nothing but running the test. > > A better way measure such artefacts is to run something like hackbench, > and compare the execution times, on kernels w/ and w/o the I-pipe. > http://developer.osdl.org/craiger/hackbench/src/hackbench.c > Tune the argument representing the number of process groups which you > pass to this program, so that it runs for a few minutes without putting > your box/board on its knees. There should be no significant difference > between the time reported at the end of both tests, at the very least, > not a 30% increase as your first report suggested. If the difference is > noticeable, then, there might be an issue (the final conclusion really > depends on the underlying hw). > -- Philippe. _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
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