Quoth Matthew Smith at 2008-07-31 11:43...
<snip/>
> In an attempt to fix any latency issues, I have used the RT-modified
> ketchup to get myself a kernel 2.6.25.8-rt7.
<snip/>
> Whilst going from the 'low-latency desktop' of my standard kernel to the
> RT kernel has made a huge difference in the number of xruns that I am
> seeing on Jack, it hasn't cured them completely.
Many thanks to those who responded on this issue - suggestions have been
taken on board and this is where we are now.
Having enquired of the linux-rt-users list, I was advised to use
2.6.24.7-rt17, being the "latest and greatest". It appears that my
issue with 2.6.25.8-rt7 is a know issue and that there are patches
available.
So, I duly built the recommended kernel and the errors in dmesg have
gone away.
I have looked at my /proc/interrupts and can't see any obvious conflicts.
However, I am now getting an almost constant stream of xruns - far worse
than when I was using a standard kernel. I tried disconnecting all my
external USB devices but the xruns continued to show up in a
never-ending stream.
Looking at the output of top and ps, there seem to be a lot of kernel
processes that weren't there before which makes me wonder if I haven't
stuffed up the configuration of the RT kernel. (I was having to guess
at the configuration values that were unfamiliar to me.)
For completeness, I should probably state that my fglrx (video) driver
no longer shows up in /proc/interrupts - the driver is incompatible with
RT kernels so I simply didn't install it. (The driver is a
closed-source one [with no available open source alternative] and the
installation process tells me to go away because it doesn't like RT or
low-latency kernels.) My X session looks fine without it, so I question
exactly what good it was doing...
Here's my /proc/interrupts:
CPU0 CPU1
0: 104035013 12175 IO-APIC-edge timer
1: 18 0 IO-APIC-edge i8042
8: 1 0 IO-APIC-edge rtc
9: 96344 17 IO-APIC-fasteoi acpi
12: 4280 0 IO-APIC-edge i8042
14: 37 0 IO-APIC-edge ide0
16: 146819 160 IO-APIC-fasteoi ahci, uhci_hcd:usb2, eth0
17: 82562 0 IO-APIC-fasteoi uhci_hcd:usb3, HDA Intel
18: 26 0 IO-APIC-fasteoi uhci_hcd:usb4
19: 81102 265 IO-APIC-fasteoi ehci_hcd:usb1, uhci_hcd:usb5
NMI: 0 0 Non-maskable interrupts
LOC: 33916179 83674441 Local timer interrupts
RES: 37665467 38976190 Rescheduling interrupts
CAL: 40 35 function call interrupts
TLB: 247574 257703 TLB shootdowns
TRM: 0 0 Thermal event interrupts
THR: 0 0 Threshold APIC interrupts
SPU: 0 0 Spurious interrupts
ERR: 0
I've posted the relevant kernel .config here:
<http://www.smiffysplace.com/files/kconfig_rt_20080803>
1) Does anyone have any idea what's going wrong?
2) Does anyone have a .config for a 2.6.24 kernel with the RT patch that
is working well with Jack that they would be willing to share? I guess
that starting from a known-good configuration would be my next logical
step unless anyone can just spot the error.
Cheers
M
--
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
LinkedIn: http://www.linkedin.com/in/smiffy
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