Wolfgang Grandegger wrote:
On 07/13/2004 02:29 PM Philippe Gerum wrote:
On Wed, 2004-07-07 at 13:37, Wolfgang Grandegger wrote:
Hi,
I have now commited a first port of RTAI over ADEOS/ppc to the vesuvio
branch. One first observation is, that the latencies and task switch
times are almost doubled on slow PowerPC processors (MPC860 at 50 MHz).
I will give some more information on this port including performance
figures later on.
It would be interesting to know if the IRQ latencies are also observable
using the irq_jitter test (or some adaptation of) from the Adeos distro
(linux/examples/* IIRC).
These figures look resonable but I cannot compare them directly with the
pre-ADEOS case. From my point of view, the bigger task switch times and
latencies are simply due to additional code to be processed, which shows
up on slow processors (with little caches, etc.). Are there any figures
for x86? I will provide some preliminary ones for PPC today or tomorrow.
The machine I've (PIII 1GHz) shows about .5 us UP switching time for
LXRT, full Linux process, and .35 us for an RTAI proper task (not safe
to be used in production work). The latter figure is practically the
same as for ksched_up. I roughly recall that NEWLXRT had something about
4 us on a plain Pentium 200 MHz for full Linux processes.
Paolo.
