Re: [LAU] Ubuntu: changing realtime priority of irqs

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To: A list for linux audio users <linux-audio-user@...>
Date: Saturday, July 21, 2007 - 4:35 pm

On Sat, 2007-07-21 at 22:26 +1000, James Cameron wrote:

Homemade (with mingo rt-patch) 2.6.18-rt7

2.6.20-16-lowlatency

> On Debian, I get ksoftirqd as well, one

Nope...

> or the

Might be...

> It may be possible to rebuild the Ubuntu kernel you are using to match

I grabbed a vanilla 2.6.22.1 and applied the latest patch and quick
testing seems to suggest that the system is running at least at well as
under debian:

atte@ajstrup:~$ uname -r
2.6.22.1-rt4

atte@ajstrup:~$ ps aux | grep IRQ
root 36 0.0 0.0 0 0 ? S< 18:15 0:00 [IRQ-9]
root 268 0.0 0.0 0 0 ? S< 18:16 0:00 [IRQ-4]
root 292 0.0 0.0 0 0 ? S< 18:16 0:00
[IRQ-12]
root 293 0.0 0.0 0 0 ? S< 18:16 0:00 [IRQ-1]
root 1108 0.0 0.0 0 0 ? S< 18:16 0:00
[IRQ-14]
root 1139 0.0 0.0 0 0 ? S< 18:16 0:00
[IRQ-15]
root 1140 0.2 0.0 0 0 ? S< 18:16 0:02
[IRQ-11]
root 1936 0.0 0.0 0 0 ? S< 18:16 0:00 [IRQ-8]
root 2025 0.0 0.0 0 0 ? S< 18:16 0:00 [IRQ-7]
root 2103 0.3 0.0 0 0 ? S< 18:16 0:03
[IRQ-10]
root 3432 0.0 0.0 0 0 ? S< 18:16 0:00 [IRQ-3]
atte 4674 0.0 0.0 2888 772 pts/2 R+ 18:33 0:00 grep
IRQ

> I've never tried setting real-time priority on kernel threads

Alot!

Bottom line: It seems it's still necessary to roll your own kernel to
get optimal realtime performance under ubuntu :-(

--
peace, love & harmony
Atte

http://atte.dk | http://myspace.com/attejensen
http://anagrammer.dk | http://atte.dk/compositions

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Messages in current thread:
Re: [LAU] Ubuntu: changing realtime priority of irqs, Florian Schmidt, (Sat Jul 21, 11:36 pm)
Re: [LAU] Ubuntu: changing realtime priority of irqs, David Causse, (Sat Jul 21, 2:04 pm)
Re: [LAU] Ubuntu: changing realtime priority of irqs, David Causse, (Sat Jul 21, 2:48 pm)
Re: [LAU] Ubuntu: changing realtime priority of irqs, Thomas Kuther, (Sat Jul 21, 12:27 pm)
Re: [LAU] Ubuntu: changing realtime priority of irqs, James Cameron, (Sat Jul 21, 12:25 pm)
Re: [LAU] Ubuntu: changing realtime priority of irqs, Atte , (Sat Jul 21, 4:35 pm)
Re: [LAU] Ubuntu: changing realtime priority of irqs, Florian Schmidt, (Sat Jul 21, 11:40 pm)