[PlanetCCRMA] Low latency kernel?

[Paquita]

Hi,

I'm running FC4 with the 2.6.13-0.3.rdt.rhfc4.ccrma kernel from the 
planetedge repository.
As I don't have a /proc/sys/kernel/lowlatency, should I conclude this 
kernel does not have the low latency patch?

The reason I'm asking is that currently, I get a 42.7 ms latency when I 
launch the Jack server with the default settings. If I try to e.g. 
listen to a Hydrogen demo song, there are very audible clicks. They 
unsurprisingly get worse if I decrease the period.

The jack default command is: /usr/bin/jackd -R -dalsa -dhw:0 -r48000 
-p1024 -n2.
hw:0 is indeed the device I want to use. It's an external USB interface:
[paquita@marlon asound]$ cat cards
0 [Duo            ]: USB-Audio - USB AudioSport Duo
                     M Audio USB AudioSport Duo at usb-0000:00:1d.7-3.2, 
full speed

and I've got this .asoundrc (I do hope to write a better one later):
[paquita@marlon ~]$ cat .asoundrc
pcm.usb-audio {
        type hw
        card 0
 }

ctl.usb-audio {
        type hw
        card 0
}

By the way, what does rdt mean in the kernel name?

Thanks in advance,
Paquita