Hi,
I have been performing some timings with the semaphores under RTAI.
I have a DUAL P-III 500 Mhz.
I find a 9 usec time between the moment a semaphore is released on one CPU
and the time a task on the other CPU is started. The initial semaphore
release is done by a user put to the rt fifo and the fifo handler make
the real call.
On the other hand, I find that with a interrupt handler, releasing a
semaphore to say task 1 running on the same CPU, it takes roughly the same
time (10 usec) but if the task is set to run on a different cpu, than the
irq hanbdler, it takes up to 16 usec.
Do these number make sense ? I run the scheduler for SMP and rtai 0.9a
with kernel 13 of linux.
I took my measurements using a outb to the paralle port.
Any comments or suggestions to speed this up ? I have been told that
Windows NT is around 5 usec ... BUT I have not seen it myself nor have
details on the timing measurement system.
Thank you
Michel
-----------------------------------
Michel Doyon, M.Eng.
Senior STVF Control Engineer
Canadian Space Agency
6767 route de l'aeroport
St-Hubert (Quebec)
J3Y 8Y9 - CANADA
Tel.: (450) 926 4679 - Fax : (450) 926 4695
[EMAIL PROTECTED]
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