As previously posted, I'm using 2.6.18 for compatibility with third
party drivers for an FPGA card. This a scene-generation app using an
Nvidia Quadro FX5800 requiring a high-frame rate with no dropped frames;
hence the need for RT (we've had previous success using proprietary
stuff but thought we'd give this a go).
It's working fine (with very occasional crashes, most of which seem to
have been referred to in later RT kernel fixes, but we can put up with
it).
Some notes for posterity:
Turn off irqbalance service
Deselect power management stuff in kernel
Select SATA IDE emulation in BIOS (otherwise no SCSI/CD stuff)
Rebuilt Broadcom tg3 and set pci=nomsi for network drivers to
function
isolcpus used on boot
App run on isolated cpus using 'taskset'
Like I said, it works fine, I haven't seen any dropped frames yet, but
there's stuff I don't understand from using other RT OSs...
All interrupts run on CPU0, all the time, there's no requirement to
use smp_affinity, in fact if you do the whole thing grinds to a halt. I
guess this is fine.
The isolcpus option seems to work fine except for the following
running on all eight CPUs:
migration
posix_cpu_timer
softirq-high
softirq-timer
softirq-net-tx
softirq-net-rx
softirq-block
softirq-tasklet
softirq-hrtimer
softirq-rcu
watchdog
desched
aio
cqueue
kblockd
events
I guess this is preemptible stuff which must run per cpu, but
there's a bit in a Red Hat page
http://rt.et.redhat.com/wiki/index.php?title=RHEL-RT_AffinityHowto&print
able=yes (starting "In MRG Realtime") which apparently refers to these
elements in their RT kernel suggesting that these should be dealt with
(but then doesn't seem to say how). Do I need to do anything about
these processes?
Thanks
John
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